389	RWTH Publication No: 230287        2014        IGPM389.pdf
TITLE	IMEX Large Time Step Finite Volume Methods for Low Froude Number Shallow Water Flows
AUTHORS	Georgij Bispen, Koottungal Revi Arun, Maria Lukáčová-Medviďová, Sebastian Noelle
ABSTRACT	We present new large time step methods for the shallow water flows in the low Froude number limit. In order to take into account multiscale phenomena that typically appear in geophysical flows nonlinear fluxes are split into a linear part governing the gravitational waves and the nonlinear advection. We propose to ap- proximate fast linear waves implicitly in time and in space by means of a genuinely multidimensional evolution operator. On the other hand, we approximate nonlinear advection part explicitly in time and in space by means of the method of charac- teristics or some standard numerical flux function. Time integration is realized by the implicit-explicit (IMEX) method. We apply the IMEX Euler scheme, two step Runge Kutta Cranck Nicolson scheme, as well as the semi-implicit BDF scheme and prove their asymptotic preserving property in the low Froude number limit. Numerical experiments demonstrate stability, accuracy and robustness of these new large time step finite volume schemes with respect to small Froude number.
KEYWORDS	low Froude number flows, asymptotic preserving schemes, shallow water equations, large time step, semi-implicit approximation, evolution Galerkin schemes
DOI	10.4208/cicp.040413.160114a
PUBLICATION	Communication in Computational Physics Volume 16 (2014), pp. 307-347.