The magnetohydrodynamic （MHD） flow and mass transfer of an electrically conducting upper convected Maxwell （UCM） fluid at a porous surface are studied in the presence of a chemically reactive species. The governin...The magnetohydrodynamic （MHD） flow and mass transfer of an electrically conducting upper convected Maxwell （UCM） fluid at a porous surface are studied in the presence of a chemically reactive species. The governing nonlinear partial differential equations along with the appropriate boundary conditions are transformed into nonlinear ordinary differential equations and numerically solved by the Keller-box method. The effects of various physical parameters on the flow and mass transfer characteristics are graphically presented and discussed. It is observed that the order of the chemical reaction is to increase the thickness of the diffusion boundary layer. Also, the mass transfer rate strongly depends on the Schmidt number and the reaction rate parameter. Furthermore, available results in the literature are obtained as a special case.展开更多
为了优化裂殖壶菌油脂胞内转乙酯化工艺条件,以DHA酯化率为指标,在单因素实验基础上采用Box-Behnken响应面实验设计,考察了无水乙醇用量、浓硫酸用量、反应温度和反应时间对裂殖壶菌油脂胞内转乙酯化的影响。结果表明:针对0.5 g干菌粉,...为了优化裂殖壶菌油脂胞内转乙酯化工艺条件,以DHA酯化率为指标,在单因素实验基础上采用Box-Behnken响应面实验设计,考察了无水乙醇用量、浓硫酸用量、反应温度和反应时间对裂殖壶菌油脂胞内转乙酯化的影响。结果表明:针对0.5 g干菌粉,得到最优的胞内转乙酯化工艺条件为无水乙醇用量11.76 m L、浓硫酸用量0.41 m L、反应温度75.5℃、反应时间2.24 h,在此条件下DHA酯化率达到85.19%。展开更多
To analyze the thermal convection of ferrofluid along a flat plate is the persistence of this study. The two-dimensional laminar, steady, incompressible flow past a flat plate subject to convective surface boundary co...To analyze the thermal convection of ferrofluid along a flat plate is the persistence of this study. The two-dimensional laminar, steady, incompressible flow past a flat plate subject to convective surface boundary condition, slip velocity in the presence of radiation has been studied where the magnetic field is applied in the transverse direction to the plate. Two different kinds of magnetic nanoparticles, magnetite Fe3O4 and cobalt ferrite CoFe2O4 are amalgamated within the base fluids water and kerosene. The effects of various physical aspects such as magnetic field, volume fraction, radiation and slip conditions on the flow and heat transfer characteristics are presented graphically and discussed. The effect of various dimensionless parameters on the skin friction coefficient and heat transfer rate are also tabulated. To investigate this particular problem, numerical computations are done using the implicit finite difference method based Keller-Box Method.展开更多
In this paper, the heat transfer effect on the steady boundary layer flow of a Casson fluid past a stretching surface in the presence of slip conditions was analyzed. The stretching surface is maintained at a constant...In this paper, the heat transfer effect on the steady boundary layer flow of a Casson fluid past a stretching surface in the presence of slip conditions was analyzed. The stretching surface is maintained at a constant temperature. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller-box finite difference scheme. The resulting equations are solved numerically by using the Kellerbox finite-difference method, and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for non-Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that both velocity and temperature decrease with an increase of the Casson fluid parameter.展开更多
<span style="font-family:Verdana;">We studied the temperature distribution and fluid velocity in a box-type solar cooker by using the Finite Element Method (FEM) in Ziguinchor southern of Senegal. Inde...<span style="font-family:Verdana;">We studied the temperature distribution and fluid velocity in a box-type solar cooker by using the Finite Element Method (FEM) in Ziguinchor southern of Senegal. Indeed, this is one of the sunniest countries in the world: more than 3000 hours of sunshine per year with an average temperature of around 30<span style="white-space:nowrap;">˚</span>C. This abundant and exploitable solar energy contributes to the development of more efficient, profitable and clean sources of energy. This will help to satisfy the increasing demand of energy. This numerical model was validated by comparing the numerical results with those of the experiment carried out on a single day. The relative error obtained is below 3%. The model results confirmed the performance of this cooker as its cooking temperature is available for more than seven hours. They have shown that the temperature and internal fluid velocity fields are not homogeneous. The results, although preliminary and encouraging, are a first step towards the complete simulation of a solar cooker integrated into a drying column.</span>展开更多
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region of China (No. HKU 715510E)
文摘The magnetohydrodynamic （MHD） flow and mass transfer of an electrically conducting upper convected Maxwell （UCM） fluid at a porous surface are studied in the presence of a chemically reactive species. The governing nonlinear partial differential equations along with the appropriate boundary conditions are transformed into nonlinear ordinary differential equations and numerically solved by the Keller-box method. The effects of various physical parameters on the flow and mass transfer characteristics are graphically presented and discussed. It is observed that the order of the chemical reaction is to increase the thickness of the diffusion boundary layer. Also, the mass transfer rate strongly depends on the Schmidt number and the reaction rate parameter. Furthermore, available results in the literature are obtained as a special case.
文摘为了优化裂殖壶菌油脂胞内转乙酯化工艺条件,以DHA酯化率为指标,在单因素实验基础上采用Box-Behnken响应面实验设计,考察了无水乙醇用量、浓硫酸用量、反应温度和反应时间对裂殖壶菌油脂胞内转乙酯化的影响。结果表明:针对0.5 g干菌粉,得到最优的胞内转乙酯化工艺条件为无水乙醇用量11.76 m L、浓硫酸用量0.41 m L、反应温度75.5℃、反应时间2.24 h,在此条件下DHA酯化率达到85.19%。
文摘To analyze the thermal convection of ferrofluid along a flat plate is the persistence of this study. The two-dimensional laminar, steady, incompressible flow past a flat plate subject to convective surface boundary condition, slip velocity in the presence of radiation has been studied where the magnetic field is applied in the transverse direction to the plate. Two different kinds of magnetic nanoparticles, magnetite Fe3O4 and cobalt ferrite CoFe2O4 are amalgamated within the base fluids water and kerosene. The effects of various physical aspects such as magnetic field, volume fraction, radiation and slip conditions on the flow and heat transfer characteristics are presented graphically and discussed. The effect of various dimensionless parameters on the skin friction coefficient and heat transfer rate are also tabulated. To investigate this particular problem, numerical computations are done using the implicit finite difference method based Keller-Box Method.
文摘In this paper, the heat transfer effect on the steady boundary layer flow of a Casson fluid past a stretching surface in the presence of slip conditions was analyzed. The stretching surface is maintained at a constant temperature. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller-box finite difference scheme. The resulting equations are solved numerically by using the Kellerbox finite-difference method, and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for non-Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that both velocity and temperature decrease with an increase of the Casson fluid parameter.
文摘<span style="font-family:Verdana;">We studied the temperature distribution and fluid velocity in a box-type solar cooker by using the Finite Element Method (FEM) in Ziguinchor southern of Senegal. Indeed, this is one of the sunniest countries in the world: more than 3000 hours of sunshine per year with an average temperature of around 30<span style="white-space:nowrap;">˚</span>C. This abundant and exploitable solar energy contributes to the development of more efficient, profitable and clean sources of energy. This will help to satisfy the increasing demand of energy. This numerical model was validated by comparing the numerical results with those of the experiment carried out on a single day. The relative error obtained is below 3%. The model results confirmed the performance of this cooker as its cooking temperature is available for more than seven hours. They have shown that the temperature and internal fluid velocity fields are not homogeneous. The results, although preliminary and encouraging, are a first step towards the complete simulation of a solar cooker integrated into a drying column.</span>
