Overview

Cerisse integrates a collection of C++ source code and libraries (such as AMReX, PelePhysics, etc.) along with the configuration of the problem setup. These pages explain how a case is initialised, detailing what problem will be solved and how.

When creating a new problem, it is best to set up a new directory (e.g., wrk) with three files:

$ls wrk
GNUmakefile	inputs prob.h

NOTE: is best to copy them from a similar example and then edit the file, this will ensure consistencty with examples. Nonetheless, the names of the input and prob.h files can change (but not the GNUmakefile). The configuration of the problem is splitted into three files.

Overview of the typical file structure

Problem definition

The definition of the problem to be solved is specified in the C++ header file prob.h (or similar), where a namespace PROB is created. This file establishes the thermodynamic and turbulence closures, as well as the numerical methods used for solving the problem. In general, it defines the equations to be solved, expressed in the form:

Here, $U$ represents a vector of conserved variables, while is a general term that includes contributions from convectie(Euler) terms, viscous terms, and source terms. Any changes to this file require the code to recompile (by running make). The tab PROB explains in detail the configuration of this file.

Compiler options

The second configuration file is the GNUMakefile. This file controls general compiler options, as well as dimensions of the problem, precision and chemistry options (if PelePhysics used). Some of these options are pased to AMReX, to ensure that only the required memory will be used and therefore faster run times. This file should probably be changed only once for every new problem. Any changes to this file require the code to be recompiled from scratch (by running make clean and then make ).

Control parameters

The third file is the input file that defines the size of the problem, gris, time-stepping, output files. This file is assumed to be modifed often and does not require recompiling. Details in here.