A33. ETD for HOMME-NH

Poster Title	Exponential Integrators for the HOMME-NH Nonhydrostatic Atmosphere Model
First Author	Cassidy Krause (Unlicensed)
Topic	computing, atmospheric model development
Affiliation	NGD Software and Algorithms
Link to document

Title

Exponential Integrators for the HOMME-NH Nonhydrostatic Atmosphere Model

Authors

Cassidy Krause, Sandia National Laboratories

Andrew Steyer, Sandia National Laboratories

Abstract

Time-stepping in the HOMME-NH nonhydrostatic atmosphere model requires integration of a stiff initial value problem. The current standard is to solve these equations using implicit-explicit (IMEX) Runge-Kutta (RK) methods with a horizontally explicit - vertically implicit (HEVI) partitioning. We introduce an exponential time differencing (ETD) scheme as an alternative to solving these stiff equations. The main drawback to exponential methods is the cost of forming the matrix exponential. Here, we show that we can mitigate this cost by taking advantage of the tridiagonal-like form of our Jacobian and parallelizing our computations, making this solver an attractive option for HOMME-NH.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

SAND2019-9005 A