In long-term rheological shear experiments with semi-solid alloys, coarsening of the particles will falsify the interpretation of the experimental results.The coarsening is intensified by the shear induced convection ...In long-term rheological shear experiments with semi-solid alloys, coarsening of the particles will falsify the interpretation of the experimental results.The coarsening is intensified by the shear induced convection and the mean size of the particles is changed significantly during the experiments.A simple model has been set up which takes the influence of the convection into account.The resulting growth law has been simplified for diffusion and convection dominated growth.The growth law was verified with shear experiments in a Searl-rheometer with A356 and tin-lead alloys.The experiments demonstrated that under convection the growth follows a linear time law and that the rate constant depends on the root of the shear rate.The correction of experimental results to gain the true viscosity function is demonstrated for a shear jump experiment with A356.展开更多
Movement of sediment load and its pattern of transportation along nearshore coastal water is a very important phenomenon to be assessed for different sector of coastal Engineering. To develop and understand the physic...Movement of sediment load and its pattern of transportation along nearshore coastal water is a very important phenomenon to be assessed for different sector of coastal Engineering. To develop and understand the physical processes responsible for shaping the ongoing evolution of the coast and to develop the management strategies to deal the impact of human activities on the coastal zone and as well as for adapting to the hazards associated with the people living on the coast, knowledge of the mechanism, processes and the pattern of sediment movement in the nearshore zone is of utmost importance. Nearshore zone is a very active area, where a series of dynamic processes occur in response to changing wave climates and sediment budgets. Nowadays mathematical modeling is an attractive alternative and becoming a very viable approach to study the sediment movement pattern with the advanced computational facilities and improved understanding on wave mechanics and sediment transport processes. It is very effective, reliable and also comfortable to study the pattern of sediment transportation including yield, distribution and management of sediment with the help of mathematical model. Validity of forecast in sediment transport depends on both mathematical modeling technique and boundary conditions.展开更多
In the last 50 years,the methodology of large-eddy simulation(LES)has been greatly developed,while lots of different subgridscale(SGS)models have appeared.However,the understanding of the procedure of SGS modeling is ...In the last 50 years,the methodology of large-eddy simulation(LES)has been greatly developed,while lots of different subgridscale(SGS)models have appeared.However,the understanding of the procedure of SGS modeling is still not clear.The present contribution aims at reviewing the recent SGS models and,more importantly,expressing our recent understanding on the SGS modeling of LES in physical space.Taking the Kolmogorov equation for filtered quantities(KEF)as an example,it is argued that the KEF alone is not enough to be a closure method.Three physical laws are then introduced to complete this closure procedure and are expected to inspire the future researches of SGS modeling.展开更多
文摘In long-term rheological shear experiments with semi-solid alloys, coarsening of the particles will falsify the interpretation of the experimental results.The coarsening is intensified by the shear induced convection and the mean size of the particles is changed significantly during the experiments.A simple model has been set up which takes the influence of the convection into account.The resulting growth law has been simplified for diffusion and convection dominated growth.The growth law was verified with shear experiments in a Searl-rheometer with A356 and tin-lead alloys.The experiments demonstrated that under convection the growth follows a linear time law and that the rate constant depends on the root of the shear rate.The correction of experimental results to gain the true viscosity function is demonstrated for a shear jump experiment with A356.
文摘Movement of sediment load and its pattern of transportation along nearshore coastal water is a very important phenomenon to be assessed for different sector of coastal Engineering. To develop and understand the physical processes responsible for shaping the ongoing evolution of the coast and to develop the management strategies to deal the impact of human activities on the coastal zone and as well as for adapting to the hazards associated with the people living on the coast, knowledge of the mechanism, processes and the pattern of sediment movement in the nearshore zone is of utmost importance. Nearshore zone is a very active area, where a series of dynamic processes occur in response to changing wave climates and sediment budgets. Nowadays mathematical modeling is an attractive alternative and becoming a very viable approach to study the sediment movement pattern with the advanced computational facilities and improved understanding on wave mechanics and sediment transport processes. It is very effective, reliable and also comfortable to study the pattern of sediment transportation including yield, distribution and management of sediment with the help of mathematical model. Validity of forecast in sediment transport depends on both mathematical modeling technique and boundary conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.11202013 and 51420105008)
文摘In the last 50 years,the methodology of large-eddy simulation(LES)has been greatly developed,while lots of different subgridscale(SGS)models have appeared.However,the understanding of the procedure of SGS modeling is still not clear.The present contribution aims at reviewing the recent SGS models and,more importantly,expressing our recent understanding on the SGS modeling of LES in physical space.Taking the Kolmogorov equation for filtered quantities(KEF)as an example,it is argued that the KEF alone is not enough to be a closure method.Three physical laws are then introduced to complete this closure procedure and are expected to inspire the future researches of SGS modeling.
