{"title":"A semi-implicit multiscale scheme for shallow water flows at low Froude number","authors":"S. Vater, R. Klein","doi":"10.2140/CAMCOS.2018.13.303","DOIUrl":"https://doi.org/10.2140/CAMCOS.2018.13.303","url":null,"abstract":"A new large time step semi-implicit multiscale method is presented for the solution of low Froude-number shallow water flows. While on small scales which are under-resolved in time the impact of source terms on the divergence of the flow is essentially balanced, on large resolved scales the scheme propagates free gravity waves with minimized diffusion. The scheme features a scale decomposition based on multigrid ideas. Two different time integrators are blended at each scale depending on the scale-dependent Courant number for gravity wave propagation. The finite-volume discretization is based on a Cartesian grid and is second order accurate. The basic properties of the method are validated by numerical tests. This development is a further step in the development of asymptotically adaptive numerical methods for the computation of large scale atmospheric flows.","PeriodicalId":49265,"journal":{"name":"Communications in Applied Mathematics and Computational Science","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2018-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76718954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"2D force constraints in the method of regularized Stokeslets","authors":"O. Maxian, Wanda Strychalski","doi":"10.2140/camcos.2019.14.149","DOIUrl":"https://doi.org/10.2140/camcos.2019.14.149","url":null,"abstract":"For many biological systems that involve elastic structures immersed in fluid, small length scales mean that inertial effects are also small, and the fluid obeys the Stokes equations. One way to solve the model equations representing such systems is through the Stokeslet, the fundamental solution to the Stokes equations, and its regularized counterpart, which treats the singularity of the velocity at points where force is applied. In two dimensions, an additional complication arises from Stokes' paradox, whereby the velocity from the Stokeslet is unbounded at infinity when the net hydrodynamic force within the domain is nonzero, invalidating the solutions. A straightforward computationally inexpensive method is presented for obtaining valid solutions to the Stokes equations for net nonzero forcing. The approach is based on imposing a mean zero velocity condition on a large curve that surrounds the domain of interest. The condition is shown to be equivalent to a net-zero force condition, where the opposite forces are applied on the large curve. The numerical method is applied to models of cellular motility and blebbing.","PeriodicalId":49265,"journal":{"name":"Communications in Applied Mathematics and Computational Science","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2018-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84352932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An adaptive local discrete convolution method\u0000for the numerical solution of Maxwell’s equations","authors":"B. Lo, P. Colella","doi":"10.2140/camcos.2019.14.105","DOIUrl":"https://doi.org/10.2140/camcos.2019.14.105","url":null,"abstract":"We present a numerical method for solving the free-space Maxwell's equations in three dimensions using compact convolution kernels on a rectangular grid. We first rewrite Maxwell's Equations as a system of wave equations with auxiliary variables and discretize its solution from the method of spherical means. The algorithm has been extended to be used on a locally-refined nested hierarchy of rectangular grids.","PeriodicalId":49265,"journal":{"name":"Communications in Applied Mathematics and Computational Science","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2018-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73919649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}