Millimeter channel reactors(MCRs)have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels.In previous studies,less work has been conducte...Millimeter channel reactors(MCRs)have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels.In previous studies,less work has been conducted on the micromixing process and enhancement strategies for non-Newtonian fluids in MCRs.In this study,the micromixing efficiency in MCRs was experimentally investigated using CMC(carboxymethyl cellulose sodium)aqueous solution to simulate a non-Newtonian fluid,and the enhanced mechanism of micromixing efficiency by the addition of internals and rotation was analyzed by computational fluid dynamics(CFD)simulations.The results show that in the conventional channel,increasing the flow rate improves the micromixing efficiency when the CMC concentration is low.However,when the CMC concentration is higher,the higher the flow rate,the lower the micromixing efficiency.The highest micromixing efficiency is obtained for the rotationally coupled inner components,followed by the single rotation and the lowest is for the internals only.CFD simulations reveal that the most effective way to improve the micromixing efficiency of non-Newtonian fluids with shear-thinning behavior is to increase the shear force in the reactor,which effectively reduces the apparent viscosity.These results provide the theoretical foundation for enhancing the micromixing process of non-Newtonian fluids in small-size reactors.展开更多
In this study,we proposed a numerical technique for solving time-dependent partial differential equations that arise in the electro-osmotic flowofCarreau fluid across a stationary plate based on amodified exponential ...In this study,we proposed a numerical technique for solving time-dependent partial differential equations that arise in the electro-osmotic flowofCarreau fluid across a stationary plate based on amodified exponential integrator.The scheme is comprised of two explicit stages.One is the exponential integrator type stage,and the second is the Runge-Kutta type stage.The spatial-dependent terms are discretized using the compact technique.The compact scheme can achieve fourth or sixth-order spatial accuracy,while the proposed scheme attains second-order temporal accuracy.Also,a mathematical model for the electro-osmotic flow of Carreau fluid over the stationary sheet is presented with heat and mass transfer effects.The governing equations are transformed into dimensionless partial differential equations and solved by the proposed scheme.Simulation results reveal that increasing the Helmholtz-Smoluchowski velocityUHS by 400%leads to a 60%-75%rise in peak flowvelocity,while the electro-osmotic parameter me enhances near-wall acceleration.Conversely,velocity decreases significantly with higher Weissenberg numbers,indicating the Carreau fluid’s elastic resistance and increased magnetic field strength due to improved Lorentz forces.Temperature rises with the thermal conductivity parameter 2,while higher reaction ratesγdiminish concentration and local Sherwood number values.The simulation findings show the scheme’s correctness and efficacy in capturing the complicated interactions in non-Newtonian electro-osmotic transport by revealing the notable impact of electrokinetic factors on flowbehaviour.Theproposedmodel is particularly relevant for BiologicalMicro-Electro-Mechanical Systems(BioMEMS)applications,where precise control of electro-thermal transport in non-Newtonian fluids is critical for lab-on-a-chip diagnostics,drug delivery,and micro-scale thermal management.展开更多
In this paper, the aim is to establish the local existence of classical solutions for a class of compressible non-Newtonian fluids with vacuum in one-dimensional bounded intervals, under the assumption that the data s...In this paper, the aim is to establish the local existence of classical solutions for a class of compressible non-Newtonian fluids with vacuum in one-dimensional bounded intervals, under the assumption that the data satisfies a natural compatibility condition. For the results, the initial density does not need to be bounded below away from zero.展开更多
The fabrication of constructs with gradients for chemical,mechanical,or electrical composition is becoming critical to achieving more complex structures,particularly in 3D printing and biofabrication.This need is unde...The fabrication of constructs with gradients for chemical,mechanical,or electrical composition is becoming critical to achieving more complex structures,particularly in 3D printing and biofabrication.This need is underscored by the complexity of in vivo tissues,which exhibit heterogeneous structures comprised of diverse cells and matrices.Drawing inspiration from the classical Tesla valve,our study introduces a new concept of micromixers to address this complexity.The innovative micromixer design is tailored to enhance the re-creation of in vivo tissue structures and demonstrates an advanced capability to efficiently mix both Newtonian and non-Newtonian fluids.Notably,our 3D Tesla valve micromixer achieves higher mixing efficiency with fewer cycles,which represents a significant improvement over the traditional mixing method.This advance is pivotal for the field of 3D printing and bioprinting,and offers a robust tool that could facilitate the development of gradient hydrogel-based constructs that could also accurately mimic the intricate heterogeneity of natural tissues.展开更多
Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate o...Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate of impeller, ventilation, rheological properties and bubble morphology in the reactor. In this perspective, through optimal computational fluid dynamics models and experiments, the relationship between power consumption, volumetric mass transfer rate(kLa) and initial bubble size(d0) was constructed to establish an efficient operation mode for the aeration process of non-Newtonian fluids. It was found that reducing the d0could significantly increase the oxygen mass transfer rate, resulting in an obvious decrease in the ventilation volume and impeller speed. When d0was regulated within 2-5 mm,an optimal kLa could be achieved, and 21% of power consumption could be saved, compared to the case of bubbles with a diameter of 10 mm.展开更多
Liquids to be broken up using a prefilming airblast atomizer are usually Newton liquids with relatively low viscosities.While in some industrial processes,such as spray drying,liquids to be atomized are high concentra...Liquids to be broken up using a prefilming airblast atomizer are usually Newton liquids with relatively low viscosities.While in some industrial processes,such as spray drying,liquids to be atomized are high concentration suspensions or non-Newtonian fluids with high viscosities.In this paper,non-Newtonian fluids with viscosity up to 4.4 Pa·s were effectively atomized using a specially designed prefilming airblast atomizer.The atomizer enabled liquid to extend to a thickness-adjustable film and forced the atomizing air stream to swirl with 30° or 45° through gas distributors with spiral slots.The liquid film was impinged by the swirling air stream resulting in the disintegration of the film into drops.Drop sizes were measured using a laser diffraction technique.An improved four-parameter mathematical model was established to relate the Sauter mean diameter of drops to the atomization conditions in terms of power dependencies on three dimensionless groups:Weber number,Ohnesorge number and air liquid mass ratio.The friction on the surface of the liquid film made by swirling air stream played an important role in the prefilming atomization at the conditions of low air velocity and low liquid viscosity.In this case,the liquid film was disintegrated into drops according to the classical wavy-sheet mechanism,thus thinner liquid films and high swirl levels of the atomizing air produced smaller drops.With the increase of the air velocity and the liquid viscosity,the effect of the friction on the prefilming atomization relatively weakened,whereas the impingement on the liquid film made by atomizing air stream in a direction normal to the liquid film and corresponding momentum transfer gradually strengthened and eventually dominated the disruption of liquid into drops,which induced that the initial thickness of the liquid film and the swirl of atomizing air stream exercised a minor influence on the drop sizes.展开更多
This paper presents analytieal solutions to the partial differential equations for unsteady flow of the second-order fluid and Maxwell fluid in tube by using the integral transform method. It can be used to analyse th...This paper presents analytieal solutions to the partial differential equations for unsteady flow of the second-order fluid and Maxwell fluid in tube by using the integral transform method. It can be used to analyse the behaviour of axial velocity and shear stress for unsteady flow of nun-Newtonian visco-elastie fluids in tube, and to provide a theoretical base for the projection of pipe-line engineering.展开更多
The present paper focuses on finding an analytical solution for fully developed third-grade non-Newtonian fluids flows inside rough circular pipes at low Reynolds numbers(Stokes flows).The wall roughness is modeled by...The present paper focuses on finding an analytical solution for fully developed third-grade non-Newtonian fluids flows inside rough circular pipes at low Reynolds numbers(Stokes flows).The wall roughness is modeled by two different periodic morphologies based on sinusoidal and triangular geometries.In this study,the relative roughness(ratio of the roughness amplitude to the pipe hydraulic diameter)is selected to be a small value,which is appropriate for the perturbation analysis.The governing parameters including the axial and radial velocity profiles,stream function,wall shear stress,pressure gradient,and friction factor are expressed in analytical formulas and they are compared to the smooth pipe.The effect of the relative roughness,the wall wave number,and the non-Newtonian parameter on the governing parameters are investigated.The results show that modeling the roughness by triangular geometry has a better prediction of pressure drop regarding the basic solution of the smooth pipe.展开更多
The amino acids are necessarily nutritious components, their diffusions in body fluid and blood that be- long to typical non-Newtonian fluid are of virtual importance to control the diffusive process and help clinical...The amino acids are necessarily nutritious components, their diffusions in body fluid and blood that be- long to typical non-Newtonian fluid are of virtual importance to control the diffusive process and help clinical treatment. In this article, a holographic interferometer has been adopted to measure the diffusivity of amino acids in non-Newtonian fluid with the use of real-time holographic interference technique. In order to prove the reliability of the experimental instrument, the diffusivities of sucrose aqueous solution at 298.15K were determined. The meas- ured result displays a satisfactory accuracy of the apparatus used. Furthermore, the diffusion coefficients of glynine, L-serine, L-threonine and L-valine in polyacrylamide (PAM) aqueous solution at 298.15K were measured, respec- tively. The experimental data were fitted by a newly proposed correlation equation based on Li’s predictive model. The calculating results by the present model are at considerably good agreement with experimental values, and the maximum average deviation is only 0.5%.展开更多
This paper presents an analytical solution to the unsteady flow of the second-order non-Newtonian fluids by the use of intergral transformation method. Based on the numerical results, the effect of non-Newtonian coeff...This paper presents an analytical solution to the unsteady flow of the second-order non-Newtonian fluids by the use of intergral transformation method. Based on the numerical results, the effect of non-Newtonian coefficient Hc and other parameters on the flow are analysed. It is shown that the annular flow has a shorter characteristic time than the general pipe flow while the correspondent velocity, average velocity have a ... nailer value for a given Hc. Else, when radii ratio keeps unchanged, the shear stress of inner wall of annular flow will change with the inner radius -compared with the general pipe flow and is always smaller than that of the outer wall.展开更多
A self-developed laser image measurement system was established to study the behavior of bubble for- mation at a single orifice in non-Newtonian polyacrylamide(PAAm)solutions.Images of bubbles were captured by a CCD c...A self-developed laser image measurement system was established to study the behavior of bubble for- mation at a single orifice in non-Newtonian polyacrylamide(PAAm)solutions.Images of bubbles were captured by a CCD camera and volumes of bubbles were digitally analyzed online.The effects of rheological property of PAAm solution,orifice,reservoir,and gas flowrate on bubble formation were studied experimentally.It is found that the volume of bubble increases with the concentration of PAAm solution,the diameter of the orifice,and the gas flowrate,respectively,whereas little effect of reservoir is observed in experiments.展开更多
This paper describes the application of a three-dimensional lattice Boltzmann method(LBM)to Newtonian and non-Newtonian(Bingham fluid in this work)flows with free surfaces.A mass tracking algorithm was incorporated to...This paper describes the application of a three-dimensional lattice Boltzmann method(LBM)to Newtonian and non-Newtonian(Bingham fluid in this work)flows with free surfaces.A mass tracking algorithm was incorporated to capture the free surface,whereas Papanastasiou's modified model was used for Bingham fluids.The lattice Boltzmann method was first validated using two benchmarks:Newtonian flow through a square cross-section tube and Bingham flow through a circular cross-section tube.Afterward,the dam-break problem for the Newtonian fluid and the slump test for Bingham fluid were simulated to validate the free-surface-capturing algorithm.The numerical results were in good agreement with analytical results,as well as other simulations,thereby proving the validity and correctness of the current method.The proposed method is a promising substitute for time-consuming and costly physical experiments to solve problems encountered in geotechnical and geological engineering,such as the surge and debris flow induced by a landslide or earthquake.展开更多
These experimental investigations are designed to study shock wave characteristics and spray structure. Supersonic liq- uid jets injected into ambient fields are empirically studied using projectile impacts in a two-s...These experimental investigations are designed to study shock wave characteristics and spray structure. Supersonic liq- uid jets injected into ambient fields are empirically studied using projectile impacts in a two-stage light gas gun. This study looks primarily at the design of the nozzle assembly, the tip velocity of the high speed jet, the structure of the spray jet and the shock wave generation process. The supersonic liquid jets were visualized using an ultra high-speed camera and the schlieren system for visualization to quantitatively analyze the shock wave angle. The experimental re- sults with straight cone nozzle types and various non-Newtonian fluid viscosities are presented in this paper. The effects of nozzle geometry on the jet behavior are described. The characteristics of the shock wave generation and spray jet structure were found to be significantly related to the nozzle geometry. The expansion gases accelerated the projectile, which had a mass of 6 grams, from 250 m/s. As a result, it was found that the maximum jet velocity appeared in the liquid jet with high viscosity properties. Supersonic liquid jets, which occurred at the leading edge the shock waves and the compression waves in front of the jets, were observed. Also, the shock waves significantly affected the atomization process for each spray droplet.展开更多
A two-dimensional （2D） stochastic incompressible non-Newtonian fluid driven by the genuine cylindrical fractional Brownian motion （FBM） is studied with the Hurst parameter ∈ （1/4,1/2） under the Dirichlet bounda...A two-dimensional （2D） stochastic incompressible non-Newtonian fluid driven by the genuine cylindrical fractional Brownian motion （FBM） is studied with the Hurst parameter ∈ （1/4,1/2） under the Dirichlet boundary condition. The existence and regularity of the stochastic convolution corresponding to the stochastic non-Newtonian fluids are obtained by the estimate on the and the identity of the infinite double series spectrum of the spatial differential operator in the analytic number theory. The existence of the mild solution and the random attractor of a random dynamical system are then obtained for the stochastic non-Newtonian systems with ∈ （1/2,1） without any additional restriction on the parameter H.展开更多
The amino acids are necessarily nutritious components, their diffusions in body fluid and blood that belong to typical non-Newtonian fluid are of virtual importance to control the diffusive process and help clini...The amino acids are necessarily nutritious components, their diffusions in body fluid and blood that belong to typical non-Newtonian fluid are of virtual importance to control the diffusive process and help clinical treatment. In this article, a holographic interferometer has been adopted to measure the diffusivity of amino acids in non-Newtonian fluid with the use of real-time holographic interference technique. In order to prove the reliability of the experimental instrument, the diffusivities of sucrose aqueous solution at 298.15K were determined. The meas- ured result displays a satisfactory accuracy of the apparatus used. Furthermore, the diffusion coefficients of glynine, L-serine, L-threonine and L-valine in polyacrylamide （PAM） aqueous solution at 298.15K were measured, respec- tively. The experimental data were fitted by a newly proposed correlation equation based on Li＇s predictive model. The calculating results by the present model are at considerably good agreement with experimental values, and the maximum average deviation is only 0.5%.展开更多
We scrutinize the approximate analytical solutions by the optimal homotopy analysis method(OHAM) for the flow and mass transfer within the Marangoni boundary layer of power-law fluids over a disk with suction and inje...We scrutinize the approximate analytical solutions by the optimal homotopy analysis method(OHAM) for the flow and mass transfer within the Marangoni boundary layer of power-law fluids over a disk with suction and injection in the present paper. Concentration distribution on the surface of a disk varies in a power-law form. The non-Newtonian fluid flow is due to the surface concentration gradient without considering gravity and buoyancy. According to the conservation of mass, momentum and concentration, the governing partial differential equations are established, and the appropriate generalized Kármán transformation is found to reduce them to the nonlinear ordinary differential equations. OHAM is used to access the approximate analytical solution. The influences of Marangoni the number, suction/injection parameters and power-law exponent on the flow and mass transfer are examined.展开更多
In this paper, the authors study the long time behavior of solutions to stochastic non-Newtonian fluids in a two-dimensional bounded domain, and prove the existence of H2-regularity random attractor.
Based on the comprehensive forces balance model, a modified model of the formation of a single bub-ble in non-Newtonian fluid under constant flowrate was developed by taking account of the effect of the ingoing gas th...Based on the comprehensive forces balance model, a modified model of the formation of a single bub-ble in non-Newtonian fluid under constant flowrate was developed by taking account of the effect of the ingoing gas through orifice as well as its variation on the radial expansion of bubble. The modified model involves the radial expansion equation of bubble surface and the forces balance equation in vertical direction of the bubble respec-tively. The shape variation of bubbles formed in polyacrylamide (PAM) aqueous solutions under various conditions was predicted numerically. The practical formation of bubbles was real-time visualized and recorded by a CCD camera and a computer by means of a special laser image measurement system. Results show that the predicted shapes of the bubbles by the present model agree well with experimental observation.展开更多
Fluid-structure-interaction （FSI） phenomenon is common in science and engineering. The fluidinvolved in an FSI problem may be non-Newtonian such as blood. A popular framework for FSIproblems is Peskin’s imm...Fluid-structure-interaction （FSI） phenomenon is common in science and engineering. The fluidinvolved in an FSI problem may be non-Newtonian such as blood. A popular framework for FSIproblems is Peskin’s immersed boundary （IB） method. However, most of the IB formulations arebased on Newtonian fluids. In this letter, we report an extension of the IB framework to FSIinvolving Oldroyd-B and FENE-P fluids in three dimensions using the lattice Boltzmann approach.The new method is tested on two FSI model problems. Numerical experiments show that themethod is conditionally stable and convergent with the first order of accuracy.展开更多
A numerical method capable is developed for handling steady laminar flow and heat trans-fer of a highly viscous power-law fluid whose density,viscosity,specific heat and thermalconductivity,vary with temperature.The g...A numerical method capable is developed for handling steady laminar flow and heat trans-fer of a highly viscous power-law fluid whose density,viscosity,specific heat and thermalconductivity,vary with temperature.The governing equations are found to be continuity,monmentumand energy expressions.Important effects such as varying viscosity,natural convection and viscousdissipation are incorporated in the theoretical model.These equations are being attracted by employing a decoupled finite element method.Galerkin’sprinciple is used to handle the momentum and continuity equations.Consistent(SU/PG)andnon-consistent(SU)streamline upwind methods are employed for the energy equation.Comparisonof calculated results and experimental data shows good agreement.Similar results are obtained withSU and SU/PG methods.Velocity and temperature profiles which provide insights into the processare also given.展开更多
基金supported by the National Natural Science Foundation of China(22078009)National Key Research Program of China(2021YFC3001102,2021YFC3001100).
文摘Millimeter channel reactors(MCRs)have received increasing attention because of their ability to enhance treatment capacity in addition to the advantages of microchannels.In previous studies,less work has been conducted on the micromixing process and enhancement strategies for non-Newtonian fluids in MCRs.In this study,the micromixing efficiency in MCRs was experimentally investigated using CMC(carboxymethyl cellulose sodium)aqueous solution to simulate a non-Newtonian fluid,and the enhanced mechanism of micromixing efficiency by the addition of internals and rotation was analyzed by computational fluid dynamics(CFD)simulations.The results show that in the conventional channel,increasing the flow rate improves the micromixing efficiency when the CMC concentration is low.However,when the CMC concentration is higher,the higher the flow rate,the lower the micromixing efficiency.The highest micromixing efficiency is obtained for the rotationally coupled inner components,followed by the single rotation and the lowest is for the internals only.CFD simulations reveal that the most effective way to improve the micromixing efficiency of non-Newtonian fluids with shear-thinning behavior is to increase the shear force in the reactor,which effectively reduces the apparent viscosity.These results provide the theoretical foundation for enhancing the micromixing process of non-Newtonian fluids in small-size reactors.
基金supported and funded by the Deanship of Scientific Research at Imam Mohammad Ibn Saud Islamic University(IMSIU)(grant number IMSIU-DDRSP2503).
文摘In this study,we proposed a numerical technique for solving time-dependent partial differential equations that arise in the electro-osmotic flowofCarreau fluid across a stationary plate based on amodified exponential integrator.The scheme is comprised of two explicit stages.One is the exponential integrator type stage,and the second is the Runge-Kutta type stage.The spatial-dependent terms are discretized using the compact technique.The compact scheme can achieve fourth or sixth-order spatial accuracy,while the proposed scheme attains second-order temporal accuracy.Also,a mathematical model for the electro-osmotic flow of Carreau fluid over the stationary sheet is presented with heat and mass transfer effects.The governing equations are transformed into dimensionless partial differential equations and solved by the proposed scheme.Simulation results reveal that increasing the Helmholtz-Smoluchowski velocityUHS by 400%leads to a 60%-75%rise in peak flowvelocity,while the electro-osmotic parameter me enhances near-wall acceleration.Conversely,velocity decreases significantly with higher Weissenberg numbers,indicating the Carreau fluid’s elastic resistance and increased magnetic field strength due to improved Lorentz forces.Temperature rises with the thermal conductivity parameter 2,while higher reaction ratesγdiminish concentration and local Sherwood number values.The simulation findings show the scheme’s correctness and efficacy in capturing the complicated interactions in non-Newtonian electro-osmotic transport by revealing the notable impact of electrokinetic factors on flowbehaviour.Theproposedmodel is particularly relevant for BiologicalMicro-Electro-Mechanical Systems(BioMEMS)applications,where precise control of electro-thermal transport in non-Newtonian fluids is critical for lab-on-a-chip diagnostics,drug delivery,and micro-scale thermal management.
基金Supported by NSFC(11201371,1331005)Natural Science Foundation of Shaanxi Province(2012JQ020)
文摘In this paper, the aim is to establish the local existence of classical solutions for a class of compressible non-Newtonian fluids with vacuum in one-dimensional bounded intervals, under the assumption that the data satisfies a natural compatibility condition. For the results, the initial density does not need to be bounded below away from zero.
基金supported by the National Key Research and Development Program of China(No.2018YFA0703000)the National Natural Science Foundation of China(No.52275294).
文摘The fabrication of constructs with gradients for chemical,mechanical,or electrical composition is becoming critical to achieving more complex structures,particularly in 3D printing and biofabrication.This need is underscored by the complexity of in vivo tissues,which exhibit heterogeneous structures comprised of diverse cells and matrices.Drawing inspiration from the classical Tesla valve,our study introduces a new concept of micromixers to address this complexity.The innovative micromixer design is tailored to enhance the re-creation of in vivo tissue structures and demonstrates an advanced capability to efficiently mix both Newtonian and non-Newtonian fluids.Notably,our 3D Tesla valve micromixer achieves higher mixing efficiency with fewer cycles,which represents a significant improvement over the traditional mixing method.This advance is pivotal for the field of 3D printing and bioprinting,and offers a robust tool that could facilitate the development of gradient hydrogel-based constructs that could also accurately mimic the intricate heterogeneity of natural tissues.
基金financial support of the National Natural Science Foundation of China(21776122).
文摘Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate of impeller, ventilation, rheological properties and bubble morphology in the reactor. In this perspective, through optimal computational fluid dynamics models and experiments, the relationship between power consumption, volumetric mass transfer rate(kLa) and initial bubble size(d0) was constructed to establish an efficient operation mode for the aeration process of non-Newtonian fluids. It was found that reducing the d0could significantly increase the oxygen mass transfer rate, resulting in an obvious decrease in the ventilation volume and impeller speed. When d0was regulated within 2-5 mm,an optimal kLa could be achieved, and 21% of power consumption could be saved, compared to the case of bubbles with a diameter of 10 mm.
文摘Liquids to be broken up using a prefilming airblast atomizer are usually Newton liquids with relatively low viscosities.While in some industrial processes,such as spray drying,liquids to be atomized are high concentration suspensions or non-Newtonian fluids with high viscosities.In this paper,non-Newtonian fluids with viscosity up to 4.4 Pa·s were effectively atomized using a specially designed prefilming airblast atomizer.The atomizer enabled liquid to extend to a thickness-adjustable film and forced the atomizing air stream to swirl with 30° or 45° through gas distributors with spiral slots.The liquid film was impinged by the swirling air stream resulting in the disintegration of the film into drops.Drop sizes were measured using a laser diffraction technique.An improved four-parameter mathematical model was established to relate the Sauter mean diameter of drops to the atomization conditions in terms of power dependencies on three dimensionless groups:Weber number,Ohnesorge number and air liquid mass ratio.The friction on the surface of the liquid film made by swirling air stream played an important role in the prefilming atomization at the conditions of low air velocity and low liquid viscosity.In this case,the liquid film was disintegrated into drops according to the classical wavy-sheet mechanism,thus thinner liquid films and high swirl levels of the atomizing air produced smaller drops.With the increase of the air velocity and the liquid viscosity,the effect of the friction on the prefilming atomization relatively weakened,whereas the impingement on the liquid film made by atomizing air stream in a direction normal to the liquid film and corresponding momentum transfer gradually strengthened and eventually dominated the disruption of liquid into drops,which induced that the initial thickness of the liquid film and the swirl of atomizing air stream exercised a minor influence on the drop sizes.
文摘This paper presents analytieal solutions to the partial differential equations for unsteady flow of the second-order fluid and Maxwell fluid in tube by using the integral transform method. It can be used to analyse the behaviour of axial velocity and shear stress for unsteady flow of nun-Newtonian visco-elastie fluids in tube, and to provide a theoretical base for the projection of pipe-line engineering.
文摘The present paper focuses on finding an analytical solution for fully developed third-grade non-Newtonian fluids flows inside rough circular pipes at low Reynolds numbers(Stokes flows).The wall roughness is modeled by two different periodic morphologies based on sinusoidal and triangular geometries.In this study,the relative roughness(ratio of the roughness amplitude to the pipe hydraulic diameter)is selected to be a small value,which is appropriate for the perturbation analysis.The governing parameters including the axial and radial velocity profiles,stream function,wall shear stress,pressure gradient,and friction factor are expressed in analytical formulas and they are compared to the smooth pipe.The effect of the relative roughness,the wall wave number,and the non-Newtonian parameter on the governing parameters are investigated.The results show that modeling the roughness by triangular geometry has a better prediction of pressure drop regarding the basic solution of the smooth pipe.
基金Supported by the National Natural Science Foundation of China (No.20476073).
文摘The amino acids are necessarily nutritious components, their diffusions in body fluid and blood that be- long to typical non-Newtonian fluid are of virtual importance to control the diffusive process and help clinical treatment. In this article, a holographic interferometer has been adopted to measure the diffusivity of amino acids in non-Newtonian fluid with the use of real-time holographic interference technique. In order to prove the reliability of the experimental instrument, the diffusivities of sucrose aqueous solution at 298.15K were determined. The meas- ured result displays a satisfactory accuracy of the apparatus used. Furthermore, the diffusion coefficients of glynine, L-serine, L-threonine and L-valine in polyacrylamide (PAM) aqueous solution at 298.15K were measured, respec- tively. The experimental data were fitted by a newly proposed correlation equation based on Li’s predictive model. The calculating results by the present model are at considerably good agreement with experimental values, and the maximum average deviation is only 0.5%.
文摘This paper presents an analytical solution to the unsteady flow of the second-order non-Newtonian fluids by the use of intergral transformation method. Based on the numerical results, the effect of non-Newtonian coefficient Hc and other parameters on the flow are analysed. It is shown that the annular flow has a shorter characteristic time than the general pipe flow while the correspondent velocity, average velocity have a ... nailer value for a given Hc. Else, when radii ratio keeps unchanged, the shear stress of inner wall of annular flow will change with the inner radius -compared with the general pipe flow and is always smaller than that of the outer wall.
基金Supported by the National Natural Science Foundation of China （No.20476073） and the Programs of Introducing Talents of Discipline to Universities （Grant No.B06006）.
文摘A self-developed laser image measurement system was established to study the behavior of bubble for- mation at a single orifice in non-Newtonian polyacrylamide(PAAm)solutions.Images of bubbles were captured by a CCD camera and volumes of bubbles were digitally analyzed online.The effects of rheological property of PAAm solution,orifice,reservoir,and gas flowrate on bubble formation were studied experimentally.It is found that the volume of bubble increases with the concentration of PAAm solution,the diameter of the orifice,and the gas flowrate,respectively,whereas little effect of reservoir is observed in experiments.
基金support from the Natural Science Foundation of China(Grant Nos.11272048,51239006 and 11572178)the Tsinghua University Initiative Scientific Research Program
文摘This paper describes the application of a three-dimensional lattice Boltzmann method(LBM)to Newtonian and non-Newtonian(Bingham fluid in this work)flows with free surfaces.A mass tracking algorithm was incorporated to capture the free surface,whereas Papanastasiou's modified model was used for Bingham fluids.The lattice Boltzmann method was first validated using two benchmarks:Newtonian flow through a square cross-section tube and Bingham flow through a circular cross-section tube.Afterward,the dam-break problem for the Newtonian fluid and the slump test for Bingham fluid were simulated to validate the free-surface-capturing algorithm.The numerical results were in good agreement with analytical results,as well as other simulations,thereby proving the validity and correctness of the current method.The proposed method is a promising substitute for time-consuming and costly physical experiments to solve problems encountered in geotechnical and geological engineering,such as the surge and debris flow induced by a landslide or earthquake.
文摘These experimental investigations are designed to study shock wave characteristics and spray structure. Supersonic liq- uid jets injected into ambient fields are empirically studied using projectile impacts in a two-stage light gas gun. This study looks primarily at the design of the nozzle assembly, the tip velocity of the high speed jet, the structure of the spray jet and the shock wave generation process. The supersonic liquid jets were visualized using an ultra high-speed camera and the schlieren system for visualization to quantitatively analyze the shock wave angle. The experimental re- sults with straight cone nozzle types and various non-Newtonian fluid viscosities are presented in this paper. The effects of nozzle geometry on the jet behavior are described. The characteristics of the shock wave generation and spray jet structure were found to be significantly related to the nozzle geometry. The expansion gases accelerated the projectile, which had a mass of 6 grams, from 250 m/s. As a result, it was found that the maximum jet velocity appeared in the liquid jet with high viscosity properties. Supersonic liquid jets, which occurred at the leading edge the shock waves and the compression waves in front of the jets, were observed. Also, the shock waves significantly affected the atomization process for each spray droplet.
基金supported by the National Natural Science Foundation of China (No.10971225)the Natural Science Foundation of Hunan Province (No.11JJ3004)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education of China(No.2009-1001)
文摘A two-dimensional （2D） stochastic incompressible non-Newtonian fluid driven by the genuine cylindrical fractional Brownian motion （FBM） is studied with the Hurst parameter ∈ （1/4,1/2） under the Dirichlet boundary condition. The existence and regularity of the stochastic convolution corresponding to the stochastic non-Newtonian fluids are obtained by the estimate on the and the identity of the infinite double series spectrum of the spatial differential operator in the analytic number theory. The existence of the mild solution and the random attractor of a random dynamical system are then obtained for the stochastic non-Newtonian systems with ∈ （1/2,1） without any additional restriction on the parameter H.
基金the National Natural Science Foundation of China （No.20476073）.
文摘The amino acids are necessarily nutritious components, their diffusions in body fluid and blood that belong to typical non-Newtonian fluid are of virtual importance to control the diffusive process and help clinical treatment. In this article, a holographic interferometer has been adopted to measure the diffusivity of amino acids in non-Newtonian fluid with the use of real-time holographic interference technique. In order to prove the reliability of the experimental instrument, the diffusivities of sucrose aqueous solution at 298.15K were determined. The meas- ured result displays a satisfactory accuracy of the apparatus used. Furthermore, the diffusion coefficients of glynine, L-serine, L-threonine and L-valine in polyacrylamide （PAM） aqueous solution at 298.15K were measured, respec- tively. The experimental data were fitted by a newly proposed correlation equation based on Li＇s predictive model. The calculating results by the present model are at considerably good agreement with experimental values, and the maximum average deviation is only 0.5%.
基金supported by the National Natural Science Foundation of China (No. 11702101)the Fundamental Research Funds for the Central Universities and the Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University (No. ZQNPY502)+2 种基金the Natural Science Foundation of Fujian Province (No. 2019J05093)Quanzhou High-Level Talents Support Plansupported by Subsidized Project for Postgraduates’ Innovative Fund in Scientific Research of Huaqiao University。
文摘We scrutinize the approximate analytical solutions by the optimal homotopy analysis method(OHAM) for the flow and mass transfer within the Marangoni boundary layer of power-law fluids over a disk with suction and injection in the present paper. Concentration distribution on the surface of a disk varies in a power-law form. The non-Newtonian fluid flow is due to the surface concentration gradient without considering gravity and buoyancy. According to the conservation of mass, momentum and concentration, the governing partial differential equations are established, and the appropriate generalized Kármán transformation is found to reduce them to the nonlinear ordinary differential equations. OHAM is used to access the approximate analytical solution. The influences of Marangoni the number, suction/injection parameters and power-law exponent on the flow and mass transfer are examined.
基金Project supported by the National Natural Science Foundation of China(Nos.11126160,11201475,11371183,and 11101356)
文摘In this paper, the authors study the long time behavior of solutions to stochastic non-Newtonian fluids in a two-dimensional bounded domain, and prove the existence of H2-regularity random attractor.
基金Supported by National Natural Science Foundation of China (No.20476073)National Programme of Introducing Talents of Discipline to Universities (No.B06006).
文摘Based on the comprehensive forces balance model, a modified model of the formation of a single bub-ble in non-Newtonian fluid under constant flowrate was developed by taking account of the effect of the ingoing gas through orifice as well as its variation on the radial expansion of bubble. The modified model involves the radial expansion equation of bubble surface and the forces balance equation in vertical direction of the bubble respec-tively. The shape variation of bubbles formed in polyacrylamide (PAM) aqueous solutions under various conditions was predicted numerically. The practical formation of bubbles was real-time visualized and recorded by a CCD camera and a computer by means of a special laser image measurement system. Results show that the predicted shapes of the bubbles by the present model agree well with experimental observation.
基金the US National Science Foundation (DMS-1522554) for the support
文摘Fluid-structure-interaction （FSI） phenomenon is common in science and engineering. The fluidinvolved in an FSI problem may be non-Newtonian such as blood. A popular framework for FSIproblems is Peskin’s immersed boundary （IB） method. However, most of the IB formulations arebased on Newtonian fluids. In this letter, we report an extension of the IB framework to FSIinvolving Oldroyd-B and FENE-P fluids in three dimensions using the lattice Boltzmann approach.The new method is tested on two FSI model problems. Numerical experiments show that themethod is conditionally stable and convergent with the first order of accuracy.
文摘A numerical method capable is developed for handling steady laminar flow and heat trans-fer of a highly viscous power-law fluid whose density,viscosity,specific heat and thermalconductivity,vary with temperature.The governing equations are found to be continuity,monmentumand energy expressions.Important effects such as varying viscosity,natural convection and viscousdissipation are incorporated in the theoretical model.These equations are being attracted by employing a decoupled finite element method.Galerkin’sprinciple is used to handle the momentum and continuity equations.Consistent(SU/PG)andnon-consistent(SU)streamline upwind methods are employed for the energy equation.Comparisonof calculated results and experimental data shows good agreement.Similar results are obtained withSU and SU/PG methods.Velocity and temperature profiles which provide insights into the processare also given.
