In the present work adaptation in meshless framework is proposed.The grid adaptation or mesh adaptation is quite well developed area in case of conventional grid based solvers and is popularly known asAdaptivemesh ref...In the present work adaptation in meshless framework is proposed.The grid adaptation or mesh adaptation is quite well developed area in case of conventional grid based solvers and is popularly known asAdaptivemesh refinement(AMR).In such cases the adaptation is done by subdividing the cells or elements into finer cells or elements.In case ofmeshlessmethods there are no cells or elements but only a cloud of points.In this work we propose to achieve the meshless adaptation by locally refining the point density in the regions demanding higher resolution.This results into an adaptive enriched cloud of points.We call this method as Adaptive Cloud Refinement(ACR).Themeshless solvers need connectivity information,which is a set of neighboring nodes.It is crucial part of meshless solvers.Obviously because of refining point density,the connectivity of nodes in such regions gets modified and hence has to be updated.An efficient connectivity update must exploit the fact that the node distribution would be largely unaffected except the region of adaptation.Hence connectivity updating needs to be done locally,only in these regions.In this paper we also present an extremely fast algorithm to update connectivity over adapted cloud called as ACU(Automatic Connectivity Update).展开更多
An alternate BGK type formulation of the Enskog equation has been recently proposed[1].It was shown that the new model has a valid H-theorem and correct thermal conductivity.We propose Lattice Boltzmann(LB)formulation...An alternate BGK type formulation of the Enskog equation has been recently proposed[1].It was shown that the new model has a valid H-theorem and correct thermal conductivity.We propose Lattice Boltzmann(LB)formulation of this new EnskogBGK model.The molecular nature of the model is verified in case of shear flow by comparing the predicted normal stress behavior by the current model with the prediction of molecular dynamics simulations.We extend the model for multiphase flow by incorporating attractive part as Vlasov type force.To validate multiphase formulation,the results of 3D simulations of a condensing bubble in a periodic box are presented.展开更多
This work proposes an extension to Boltzmann BGK equation for dense gases.The present model has an H-theorem and it allows choice of the Prandtl number as an independent parameter.I show that similar to Enskog equatio...This work proposes an extension to Boltzmann BGK equation for dense gases.The present model has an H-theorem and it allows choice of the Prandtl number as an independent parameter.I show that similar to Enskog equation this equation can reproduce dynamics of dense gases.展开更多
The exact solution to the hierarchy of nonlinear lattice Boltzmann kinetic equations,for the stationary planar Couette flow for any Knudsen number was presented by S.Ansumali et al.[Phys.Rev.Lett.,98(2007),124502].In ...The exact solution to the hierarchy of nonlinear lattice Boltzmann kinetic equations,for the stationary planar Couette flow for any Knudsen number was presented by S.Ansumali et al.[Phys.Rev.Lett.,98(2007),124502].In this paper,simulation results at a non-vanishing value of the Knudsen number are compared with the closed-form solutions for the higher-order moments.The order of convergence to the exact solution is also studied.The lattice Boltzmann simulations are in excellent agreement with the exact solution.展开更多
In this paper,we highlight the benefits resulting from imposing energyconserving equilibria in entropic lattice Boltzmann models for isothermal flows.The advantages are documented through a series of numerical simulat...In this paper,we highlight the benefits resulting from imposing energyconserving equilibria in entropic lattice Boltzmann models for isothermal flows.The advantages are documented through a series of numerical simulations,such as TaylorGreen vortices,cavity flow and flow past a sphere.展开更多
文摘In the present work adaptation in meshless framework is proposed.The grid adaptation or mesh adaptation is quite well developed area in case of conventional grid based solvers and is popularly known asAdaptivemesh refinement(AMR).In such cases the adaptation is done by subdividing the cells or elements into finer cells or elements.In case ofmeshlessmethods there are no cells or elements but only a cloud of points.In this work we propose to achieve the meshless adaptation by locally refining the point density in the regions demanding higher resolution.This results into an adaptive enriched cloud of points.We call this method as Adaptive Cloud Refinement(ACR).Themeshless solvers need connectivity information,which is a set of neighboring nodes.It is crucial part of meshless solvers.Obviously because of refining point density,the connectivity of nodes in such regions gets modified and hence has to be updated.An efficient connectivity update must exploit the fact that the node distribution would be largely unaffected except the region of adaptation.Hence connectivity updating needs to be done locally,only in these regions.In this paper we also present an extremely fast algorithm to update connectivity over adapted cloud called as ACU(Automatic Connectivity Update).
基金ICAM-I2CAM,1 Shields Avenue,Davis,CA 95616 for travel support through NSF grant number DMR-0844115 for attending DSFD2012 where this work was presentedDepartment of Science and Technology(DST),India for providing computational resources via Ramanujan Fellowship grant.
文摘An alternate BGK type formulation of the Enskog equation has been recently proposed[1].It was shown that the new model has a valid H-theorem and correct thermal conductivity.We propose Lattice Boltzmann(LB)formulation of this new EnskogBGK model.The molecular nature of the model is verified in case of shear flow by comparing the predicted normal stress behavior by the current model with the prediction of molecular dynamics simulations.We extend the model for multiphase flow by incorporating attractive part as Vlasov type force.To validate multiphase formulation,the results of 3D simulations of a condensing bubble in a periodic box are presented.
文摘This work proposes an extension to Boltzmann BGK equation for dense gases.The present model has an H-theorem and it allows choice of the Prandtl number as an independent parameter.I show that similar to Enskog equation this equation can reproduce dynamics of dense gases.
基金The authors acknowledge useful discussions with Dr.I.V.Karlin.N.I.Prasianakis was supported by the BFE project 103078.S.
文摘The exact solution to the hierarchy of nonlinear lattice Boltzmann kinetic equations,for the stationary planar Couette flow for any Knudsen number was presented by S.Ansumali et al.[Phys.Rev.Lett.,98(2007),124502].In this paper,simulation results at a non-vanishing value of the Knudsen number are compared with the closed-form solutions for the higher-order moments.The order of convergence to the exact solution is also studied.The lattice Boltzmann simulations are in excellent agreement with the exact solution.
基金Department of Science and Technology(DST),India for providing computational resources via Ramanujan Fellowship grantproviding financial support and kind hospitality through the Raman Chair of the Indian Academy of Sciences.
文摘In this paper,we highlight the benefits resulting from imposing energyconserving equilibria in entropic lattice Boltzmann models for isothermal flows.The advantages are documented through a series of numerical simulations,such as TaylorGreen vortices,cavity flow and flow past a sphere.
