In order to improve the overall resilience of the urban infrastructures, it is required to conduct blast resistant design for important building structures in the city. For complex terrain in the city, it is recommend...In order to improve the overall resilience of the urban infrastructures, it is required to conduct blast resistant design for important building structures in the city. For complex terrain in the city, it is recommended to determine the blast load on the structures via numerical simulation. Since the mesh size of the numerical model highly depends on the explosion scenario, there is no generally applicable approach for the mesh size selection. An efficient method to determine the mesh size of the numerical model of near-ground detonation based on explosion scenarios is proposed in this study. The effect of mesh size on the propagation of blast wave under different explosive weights was studied, and the correlations between the mesh size effect and the charge weight or the scaled distance was described. Based on the principle of the finite element method and Hopkinson-Cranz scaling law, a mesh size measurement unit related to the explosive weight was proposed as the criterion for determining the mesh size in the numerical simulation. Finally, the applicability of the method proposed in this paper was verified by comparing the results from numerical simulation and the explosion tests and was verified in AUTODYN.展开更多
Meroplankton play a crucial role in both benthic and pelagic ecosystems.Existing quantitative research on estimating the quantities of meroplankton groups is both underrepresented and inaccurate.To investigate and eva...Meroplankton play a crucial role in both benthic and pelagic ecosystems.Existing quantitative research on estimating the quantities of meroplankton groups is both underrepresented and inaccurate.To investigate and evaluate the influence of varying mesh sizes(505 and 160μm)on the sampling efficiency of meroplankton,we conducted an examination using two commonly used plankton nets during the spring season in the Southern Yellow Sea(SYS).Our study revealed a total of 12 meroplankton groups,with 9 groups identified in the 505-μm mesh nets and 11 groups in the 160-μm mesh nets.The results demonstrated the superior collection efficiency of the 160-μm net compared to the 505-μm net across the majority of meroplankton groups.Furthermore,we focused on exploring the abundance,distribution patterns,and realized niches of meroplankton collected by the two mesh size nets,and observed that the distribution of meroplankton closely resembled the distribution of possible benthic adults in the SYS.Correlation analysis of the six dominant groups collected in the 160-μm mesh nets revealed that seawater temperature and salinity emerged as the key environmental factors driving variations in meroplankton abundance within the SYS.This study also found that a smaller mesh size net does not necessarily capture meroplankton more comprehensively.A comprehensive understanding of the ecological characteristics of meroplankton requires the combination of two types of nets for research.Our research significantly advances our understanding of the quantification,abundance,and distribution of meroplankton,serving as a valuable contribution to the broader landscape of detailed quantitative meroplankton studies.展开更多
Numerical method is popular in analysing the blast wave propagation and interaction with structures.However,because of the extremely short duration of blast wave and energy trans-mission between different grids,the nu...Numerical method is popular in analysing the blast wave propagation and interaction with structures.However,because of the extremely short duration of blast wave and energy trans-mission between different grids,the numerical results are sensitive to the finite element mesh size.Previous numerical simulations show that a mesh size acceptable to one blast scenario might not be proper for another case,even though the difference between the two scenarios is very small,indicating a simple numerical mesh size convergence test might not be enough to guarantee accu-rate numerical results.Therefore,both coarse mesh and fine mesh were used in different blast scenarios to investigate the mesh size effect on numerical results of blast wave propagation and interaction with structures.Based on the numerical results and their comparison with field test re-sults and the design charts in TM5-1300,a numerical modification method was proposed to correct the influence of the mesh size on the simulated results.It can be easily used to improve the accu-racy of the numerical results of blast wave propagation and blast loads on structures.展开更多
Zooplankton samples were collected using 505, 160 and 77 μm mesh nets around a power plant during four seasons in 2011. We measured total length of zooplankton and divided zooplankton into seven size classes in order...Zooplankton samples were collected using 505, 160 and 77 μm mesh nets around a power plant during four seasons in 2011. We measured total length of zooplankton and divided zooplankton into seven size classes in order to explore how zooplankton community size-structure might be altered by thermal discharge from power plant. The total length of zooplankton varied from 93.7 to 40 074.7 μm. The spatial distribution of mesozooplankton(200-2 000 μm) populations were rarely affected by thermal discharge, while macro-(2 000-10 000 μm)and megalo-zooplankton(>10 000 μm) had an obvious tendency to migrate away from the outfall of power plant.Thus, zooplankton community tended to become smaller and biodiversity reduced close to power plant.Moreover, we compared the zooplankton communities in three different mesh size nets. Species richness,abundance, evenness index and Shannon-Wiener diversity index of the 505 μm mesh size were significantly lower than those recorded from the 160 and 77 μm mesh size. Average zooplankton abundance was highest in the 77 μm mesh net((27 690.0±1 633.7) ind./m^3), followed by 160 μm mesh net((9 531.1±1 079.5) ind./m^3), and lowest in 505 μm mesh net((494.4±104.7) ind./m^3). The ANOSIM and SIMPER tests confirmed that these differences were mainly due to small zooplankton and early developmental stages of zooplankton. It is the first time to use the 77 μm mesh net to sample zooplankton in such an environment. The 77 μm mesh net had the overwhelming abundance of the copepod genus Oithona, as an order of magnitude greater than recorded for 160 μm mesh net and 100% loss through the 505 μm mesh net. These results indicate that the use of a small or even multiple sampling net is necessary to accurately quantify entire zooplankton community around coastal power plant.展开更多
Tension-free vaginal mesh (TVM) surgery is a common and minimally invasive procedure for pelvic organ prolapses. Since commercial kits are not readily available in Japan, we have planned tailor-made mesh by informatio...Tension-free vaginal mesh (TVM) surgery is a common and minimally invasive procedure for pelvic organ prolapses. Since commercial kits are not readily available in Japan, we have planned tailor-made mesh by information of each patient before every TVM surgery. The aim of this report is to inform methods to design mesh for individual patients with pelvic organ prolapses. We also investigated the correlations among mesh size and height, weight, and body mass index (BMI). Before the operation, we obtained a KUB (abdominal X-ray). Three factors were measured from this X-ray: the first was the distance between the bilateral ischial spine, the second was the distance between the obturator foramen, and the third was the length of the arcus tendineus fascia pelvis (ATFP). These three factors always should be considered for designing of mesh. The correlations among the bilateral ischial spine distance, obturator foramen distance, ATFP length, height, weight, and BMI were assessed using the Pearson correlation coefficient. Although these three factors described above are necessary to design a mesh for individual patients, the bilateral ischial spine and obturator foramen distance correlated with the height of the patient. On the other hand, since the length of ATFP differs in each patient and is not correlated with height, we should consider this length when we design the mesh. Well-designed, tailor-made mesh will probably fit each pelvic organ prolapsed patient very well.展开更多
Over the past few decades, it has become widely recognized that the management strategies of world fisheries must ensure sustainability of target species. The intervening years have seen many improvements to the conce...Over the past few decades, it has become widely recognized that the management strategies of world fisheries must ensure sustainability of target species. The intervening years have seen many improvements to the concept of gear selectivity and methods for measuring the selectivity of fishing towed gears. Improved understanding of the principles of the selection of fish by gears has changed the list of parameters which are known to have a significant effect upon selection. The recent development of new mathematical models and the increased availability of powerful computers have resulted in improvements in the analysis procedures for the data produced to measure a gear’s selectivity. The catch of mackerel in the gulfofGuineahas steeply declined during the last two decades, and resource management is clearly required. Therefore, the need for evaluation of trawl codends used in this fishery and the potential improvements to their selectivity are of prime importance. In this paper, we use semi-empirical models to define selective properties of pelagic trawl codends targeting black mackerel (Trachurus spp) in theGulfofGuinea. These properties are determined using the experimental and theoretical methods of assessing the parameters of the selectivity curve, and by plotting the curve. Selection parameters were obtained by fitting a logistic equation using a maximum likelihood method. Trawl codend selectivity is estimated for 17 internal diamond mesh sizes in the range 47 - 79 mm. Using the basic selectivity equations, we determine the needed mesh size A = 58 mm for fishing mackerel in the gulf of Guinea. This nominal mesh size gives room for nj = 0.1 catch of juveniles, which not exceeds the allowable proportion [nj] = 0.1. To provide resource conservation, there is the need to make amendments in the fishery regulations for more rational exploitation of mackerel stoks, because the currently use nominal mesh size A = 56 mm is rather unselective.展开更多
The accuracy of numerical computation heavily relies on appropriate meshing,whichserves as the foundation for numerical computation.Although adaptive refinement methods areavailable,an adaptive numerical solution is l...The accuracy of numerical computation heavily relies on appropriate meshing,whichserves as the foundation for numerical computation.Although adaptive refinement methods areavailable,an adaptive numerical solution is likely to be ineffective if it originates from a poorly ini-tial mesh.Therefore,it is crucial to generate meshes that accurately capture the geometric features.As an indispensable input in meshing methods,the Mesh Size Function(MSF)determines the qual-ity of the generated mesh.However,the current generation of MSF involves human participation tospecify numerous parameters,leading to difficulties in practical usage.Considering the capacity ofmachine learning to reveal the latent relationships within data,this paper proposes a novel machinelearning method,Implicit Geometry Neural Network(IGNN),for automatic prediction of appro-priate MSFs based on the existing mesh data,enabling the generation of unstructured meshes thatalign precisely with geometric features.IGNN employs the generative adversarial theory to learnthe mapping between the implicit representation of the geometry(Signed Distance Function,SDF)and the corresponding MSF.Experimental results show that the proposed method is capableof automatically generating appropriate meshes and achieving comparable meshing results com-pared to traditional methods.This paper demonstrates the possibility of significantly decreasingthe workload of mesh generation using machine learning techniques,and it is expected to increasethe automation level of mesh generation.展开更多
In south-eastern Australia,the same baited,round traps(comprising 50–57-mm mesh netting)are used to target giant mud,Scylla serrata and blue swimmer crabs,Portunus armatus in spatially separated fisheries.Both fisher...In south-eastern Australia,the same baited,round traps(comprising 50–57-mm mesh netting)are used to target giant mud,Scylla serrata and blue swimmer crabs,Portunus armatus in spatially separated fisheries.Both fisheries are characterised by the common,problematic discarding of undersized portunids(<85 and 65 mm carapace length;CL for S.serrata and P.armatus)and fish(yellowfin bream,Acanthopagrus australis).This poor selectivity was addressed here in two experiments assessing the utility of(1)traps partially or completely covered in larger mesh(91 mm to match the minimum legal size of the smaller P.armatus),and then(2)any cumulative benefits of fitting species-specific escape gaps.In experiment 1,there were no differences among catches of legal-sized portunids associated with either partial,or complete trap coverage with larger mesh.Irrespective of mesh coverage,both designs of 91-mm traps also retained significantly fewer(by up to 42%)undersized P.armatus and A.australis.In experiment 2,replicate traps completely covered in 91-mm mesh were tested against conventional traps comprising 56-mm mesh,and traps with the same mesh sizes,but also three escape gaps configured for either S.serrata(46×120 mm)or P.armatus(36×120 mm)(i.e.four treatments in total).All modified traps maintained catches of legal-sized S.serrata,and only the 91-mm traps with escape gaps caught fewer legal-sized P.armatus.Fewer undersized S.serrata,P.armatus and A.australis(mean catches reduced by up to 49%)were retained in all larger-meshed than small-meshed traps,and in all of those traps with escape gaps(by up to 95%)than without.While there were no significant cumulative benefits of escape gaps in largermeshed traps(measured by a statistical interaction),there was a trend of fewer unwanted catches overall.These data support configuring portunid traps with mesh sizes matching the morphology of the smallest legal-sized target species.But,simply retroactively fitting escape gaps in existing,smaller-meshed traps will also realize positive selectivity benefits.展开更多
In this paper,a scaling law relating the mesh size to the Reynolds number was proposed to ensure consistent results for large eddy simulation(LES)as the Reynolds number was varied.The grid size scaling law was develop...In this paper,a scaling law relating the mesh size to the Reynolds number was proposed to ensure consistent results for large eddy simulation(LES)as the Reynolds number was varied.The grid size scaling law was developed by analyzing the lengthscale of the turbulent motion by using DNS data from the literature.The wall-resolving LES was then applied to a plane channel flow to validate the scaling law.The scaling law was tested at different Reynolds numbers(Ret=395,590 and 1000),and showed good results compared to direct numerical simulation(DNS)in terms of mean flow and various turbulent statistics.The velocity spectra analysis shows the evidence of the Kolmogorov–5/3 inertial subrange and verifies that the current LES can resolve the bulk of the turbulent kinetic energy by satisfying the grid scaling law.Meanwhile,the near-wall turbulent flow structures can also be well captured.Reasonably accurate predictions can thus be obtained for flows at even higher Reynolds numbers with significantly lower computational costs compared to DNS by applying the mesh scaling law.展开更多
Sphere packing is an attractive way to generate high quality mesh. Several algorithms have been proposed in this topic, however these algorithms are not sufficiently fast for large scale problems. The paper presents a...Sphere packing is an attractive way to generate high quality mesh. Several algorithms have been proposed in this topic, however these algorithms are not sufficiently fast for large scale problems. The paper presents an efficient sphere packing algorithm which is much faster and appears to be the most practical among all sphere packing methods presented so far for mesh generation. The algorithm packs spheres inside a domain using advancing front method. High efficiency has resulted from a concept of 4R measure, which localizes all the computations involved in the whole sphere packing process.展开更多
基金the funding supports of the National Key Research and Development Plan,China(Grant No.2022YFC3801800)National Natural Science Foundation of China(Grant Nos.52038010 and 52078368)。
文摘In order to improve the overall resilience of the urban infrastructures, it is required to conduct blast resistant design for important building structures in the city. For complex terrain in the city, it is recommended to determine the blast load on the structures via numerical simulation. Since the mesh size of the numerical model highly depends on the explosion scenario, there is no generally applicable approach for the mesh size selection. An efficient method to determine the mesh size of the numerical model of near-ground detonation based on explosion scenarios is proposed in this study. The effect of mesh size on the propagation of blast wave under different explosive weights was studied, and the correlations between the mesh size effect and the charge weight or the scaled distance was described. Based on the principle of the finite element method and Hopkinson-Cranz scaling law, a mesh size measurement unit related to the explosive weight was proposed as the criterion for determining the mesh size in the numerical simulation. Finally, the applicability of the method proposed in this paper was verified by comparing the results from numerical simulation and the explosion tests and was verified in AUTODYN.
基金Supported by the Laoshan Laboratory(Nos.LSKJ 202203700,LSKJ 202203704,LSKJ 202204005)the National Natural Science Foundation of China(NSFC)(Nos.42076166,42130411)the NSFC Ship Time Sharing Project(No.42149901)。
文摘Meroplankton play a crucial role in both benthic and pelagic ecosystems.Existing quantitative research on estimating the quantities of meroplankton groups is both underrepresented and inaccurate.To investigate and evaluate the influence of varying mesh sizes(505 and 160μm)on the sampling efficiency of meroplankton,we conducted an examination using two commonly used plankton nets during the spring season in the Southern Yellow Sea(SYS).Our study revealed a total of 12 meroplankton groups,with 9 groups identified in the 505-μm mesh nets and 11 groups in the 160-μm mesh nets.The results demonstrated the superior collection efficiency of the 160-μm net compared to the 505-μm net across the majority of meroplankton groups.Furthermore,we focused on exploring the abundance,distribution patterns,and realized niches of meroplankton collected by the two mesh size nets,and observed that the distribution of meroplankton closely resembled the distribution of possible benthic adults in the SYS.Correlation analysis of the six dominant groups collected in the 160-μm mesh nets revealed that seawater temperature and salinity emerged as the key environmental factors driving variations in meroplankton abundance within the SYS.This study also found that a smaller mesh size net does not necessarily capture meroplankton more comprehensively.A comprehensive understanding of the ecological characteristics of meroplankton requires the combination of two types of nets for research.Our research significantly advances our understanding of the quantification,abundance,and distribution of meroplankton,serving as a valuable contribution to the broader landscape of detailed quantitative meroplankton studies.
基金Supported by National Natural Science Foundation of China (No.50638030, 50528808)the National Key Technologies R&D Program of China (No.2006BAJ13B02)the Australian Research Council (No.DP0774061).
文摘Numerical method is popular in analysing the blast wave propagation and interaction with structures.However,because of the extremely short duration of blast wave and energy trans-mission between different grids,the numerical results are sensitive to the finite element mesh size.Previous numerical simulations show that a mesh size acceptable to one blast scenario might not be proper for another case,even though the difference between the two scenarios is very small,indicating a simple numerical mesh size convergence test might not be enough to guarantee accu-rate numerical results.Therefore,both coarse mesh and fine mesh were used in different blast scenarios to investigate the mesh size effect on numerical results of blast wave propagation and interaction with structures.Based on the numerical results and their comparison with field test re-sults and the design charts in TM5-1300,a numerical modification method was proposed to correct the influence of the mesh size on the simulated results.It can be easily used to improve the accu-racy of the numerical results of blast wave propagation and blast loads on structures.
基金The National Key Research and Development Program of China under contract No.2018YFD0900702the K.C.Wong Magna Fund in Ningbo University(SS)。
文摘Zooplankton samples were collected using 505, 160 and 77 μm mesh nets around a power plant during four seasons in 2011. We measured total length of zooplankton and divided zooplankton into seven size classes in order to explore how zooplankton community size-structure might be altered by thermal discharge from power plant. The total length of zooplankton varied from 93.7 to 40 074.7 μm. The spatial distribution of mesozooplankton(200-2 000 μm) populations were rarely affected by thermal discharge, while macro-(2 000-10 000 μm)and megalo-zooplankton(>10 000 μm) had an obvious tendency to migrate away from the outfall of power plant.Thus, zooplankton community tended to become smaller and biodiversity reduced close to power plant.Moreover, we compared the zooplankton communities in three different mesh size nets. Species richness,abundance, evenness index and Shannon-Wiener diversity index of the 505 μm mesh size were significantly lower than those recorded from the 160 and 77 μm mesh size. Average zooplankton abundance was highest in the 77 μm mesh net((27 690.0±1 633.7) ind./m^3), followed by 160 μm mesh net((9 531.1±1 079.5) ind./m^3), and lowest in 505 μm mesh net((494.4±104.7) ind./m^3). The ANOSIM and SIMPER tests confirmed that these differences were mainly due to small zooplankton and early developmental stages of zooplankton. It is the first time to use the 77 μm mesh net to sample zooplankton in such an environment. The 77 μm mesh net had the overwhelming abundance of the copepod genus Oithona, as an order of magnitude greater than recorded for 160 μm mesh net and 100% loss through the 505 μm mesh net. These results indicate that the use of a small or even multiple sampling net is necessary to accurately quantify entire zooplankton community around coastal power plant.
文摘Tension-free vaginal mesh (TVM) surgery is a common and minimally invasive procedure for pelvic organ prolapses. Since commercial kits are not readily available in Japan, we have planned tailor-made mesh by information of each patient before every TVM surgery. The aim of this report is to inform methods to design mesh for individual patients with pelvic organ prolapses. We also investigated the correlations among mesh size and height, weight, and body mass index (BMI). Before the operation, we obtained a KUB (abdominal X-ray). Three factors were measured from this X-ray: the first was the distance between the bilateral ischial spine, the second was the distance between the obturator foramen, and the third was the length of the arcus tendineus fascia pelvis (ATFP). These three factors always should be considered for designing of mesh. The correlations among the bilateral ischial spine distance, obturator foramen distance, ATFP length, height, weight, and BMI were assessed using the Pearson correlation coefficient. Although these three factors described above are necessary to design a mesh for individual patients, the bilateral ischial spine and obturator foramen distance correlated with the height of the patient. On the other hand, since the length of ATFP differs in each patient and is not correlated with height, we should consider this length when we design the mesh. Well-designed, tailor-made mesh will probably fit each pelvic organ prolapsed patient very well.
文摘Over the past few decades, it has become widely recognized that the management strategies of world fisheries must ensure sustainability of target species. The intervening years have seen many improvements to the concept of gear selectivity and methods for measuring the selectivity of fishing towed gears. Improved understanding of the principles of the selection of fish by gears has changed the list of parameters which are known to have a significant effect upon selection. The recent development of new mathematical models and the increased availability of powerful computers have resulted in improvements in the analysis procedures for the data produced to measure a gear’s selectivity. The catch of mackerel in the gulfofGuineahas steeply declined during the last two decades, and resource management is clearly required. Therefore, the need for evaluation of trawl codends used in this fishery and the potential improvements to their selectivity are of prime importance. In this paper, we use semi-empirical models to define selective properties of pelagic trawl codends targeting black mackerel (Trachurus spp) in theGulfofGuinea. These properties are determined using the experimental and theoretical methods of assessing the parameters of the selectivity curve, and by plotting the curve. Selection parameters were obtained by fitting a logistic equation using a maximum likelihood method. Trawl codend selectivity is estimated for 17 internal diamond mesh sizes in the range 47 - 79 mm. Using the basic selectivity equations, we determine the needed mesh size A = 58 mm for fishing mackerel in the gulf of Guinea. This nominal mesh size gives room for nj = 0.1 catch of juveniles, which not exceeds the allowable proportion [nj] = 0.1. To provide resource conservation, there is the need to make amendments in the fishery regulations for more rational exploitation of mackerel stoks, because the currently use nominal mesh size A = 56 mm is rather unselective.
基金co-supported by the Aeronautical Science Foundation of China(Nos.2018ZA52002 and 2019ZA052011)。
文摘The accuracy of numerical computation heavily relies on appropriate meshing,whichserves as the foundation for numerical computation.Although adaptive refinement methods areavailable,an adaptive numerical solution is likely to be ineffective if it originates from a poorly ini-tial mesh.Therefore,it is crucial to generate meshes that accurately capture the geometric features.As an indispensable input in meshing methods,the Mesh Size Function(MSF)determines the qual-ity of the generated mesh.However,the current generation of MSF involves human participation tospecify numerous parameters,leading to difficulties in practical usage.Considering the capacity ofmachine learning to reveal the latent relationships within data,this paper proposes a novel machinelearning method,Implicit Geometry Neural Network(IGNN),for automatic prediction of appro-priate MSFs based on the existing mesh data,enabling the generation of unstructured meshes thatalign precisely with geometric features.IGNN employs the generative adversarial theory to learnthe mapping between the implicit representation of the geometry(Signed Distance Function,SDF)and the corresponding MSF.Experimental results show that the proposed method is capableof automatically generating appropriate meshes and achieving comparable meshing results com-pared to traditional methods.This paper demonstrates the possibility of significantly decreasingthe workload of mesh generation using machine learning techniques,and it is expected to increasethe automation level of mesh generation.
基金This study was funded by Hunter Local Land Services and the NSW Department of Primary Industries,and would not have been possible without the assistance of Wallis Lake commercial fishers,and especially,Malcolm,Adrian and Danny.
文摘In south-eastern Australia,the same baited,round traps(comprising 50–57-mm mesh netting)are used to target giant mud,Scylla serrata and blue swimmer crabs,Portunus armatus in spatially separated fisheries.Both fisheries are characterised by the common,problematic discarding of undersized portunids(<85 and 65 mm carapace length;CL for S.serrata and P.armatus)and fish(yellowfin bream,Acanthopagrus australis).This poor selectivity was addressed here in two experiments assessing the utility of(1)traps partially or completely covered in larger mesh(91 mm to match the minimum legal size of the smaller P.armatus),and then(2)any cumulative benefits of fitting species-specific escape gaps.In experiment 1,there were no differences among catches of legal-sized portunids associated with either partial,or complete trap coverage with larger mesh.Irrespective of mesh coverage,both designs of 91-mm traps also retained significantly fewer(by up to 42%)undersized P.armatus and A.australis.In experiment 2,replicate traps completely covered in 91-mm mesh were tested against conventional traps comprising 56-mm mesh,and traps with the same mesh sizes,but also three escape gaps configured for either S.serrata(46×120 mm)or P.armatus(36×120 mm)(i.e.four treatments in total).All modified traps maintained catches of legal-sized S.serrata,and only the 91-mm traps with escape gaps caught fewer legal-sized P.armatus.Fewer undersized S.serrata,P.armatus and A.australis(mean catches reduced by up to 49%)were retained in all larger-meshed than small-meshed traps,and in all of those traps with escape gaps(by up to 95%)than without.While there were no significant cumulative benefits of escape gaps in largermeshed traps(measured by a statistical interaction),there was a trend of fewer unwanted catches overall.These data support configuring portunid traps with mesh sizes matching the morphology of the smallest legal-sized target species.But,simply retroactively fitting escape gaps in existing,smaller-meshed traps will also realize positive selectivity benefits.
文摘In this paper,a scaling law relating the mesh size to the Reynolds number was proposed to ensure consistent results for large eddy simulation(LES)as the Reynolds number was varied.The grid size scaling law was developed by analyzing the lengthscale of the turbulent motion by using DNS data from the literature.The wall-resolving LES was then applied to a plane channel flow to validate the scaling law.The scaling law was tested at different Reynolds numbers(Ret=395,590 and 1000),and showed good results compared to direct numerical simulation(DNS)in terms of mean flow and various turbulent statistics.The velocity spectra analysis shows the evidence of the Kolmogorov–5/3 inertial subrange and verifies that the current LES can resolve the bulk of the turbulent kinetic energy by satisfying the grid scaling law.Meanwhile,the near-wall turbulent flow structures can also be well captured.Reasonably accurate predictions can thus be obtained for flows at even higher Reynolds numbers with significantly lower computational costs compared to DNS by applying the mesh scaling law.
基金the National Natural Science Foundation of China (10602002 and 10772005)
文摘Sphere packing is an attractive way to generate high quality mesh. Several algorithms have been proposed in this topic, however these algorithms are not sufficiently fast for large scale problems. The paper presents an efficient sphere packing algorithm which is much faster and appears to be the most practical among all sphere packing methods presented so far for mesh generation. The algorithm packs spheres inside a domain using advancing front method. High efficiency has resulted from a concept of 4R measure, which localizes all the computations involved in the whole sphere packing process.
