This module was developed by ATA Engineering as an add-on to the Loci/CHEM computational fluid dynamics (CFD) solver. The module can be used to reduce reflections into the domain caused by boundary conditions. The module works by adding a source term to the governing equations. The purpose of the source term is to drive the flow to a user defined reference state in the sponge layer region of influence.
This module depends on both Loci and CHEM being installed. Loci is an open source framework developed at Mississippi State University (MSU) by Dr. Ed Luke. The framework provides a rule-based programming model and can take advantage of massively parallel high performance computing systems. CHEM is a full featured open source CFD code with finite-rate chemistry built on the Loci framework. CHEM is export controlled under the International Traffic In Arms Regulations (ITAR). Both Loci and CHEM can be obtained from the SimSys Software Forum hosted by MSU.
First Loci and CHEM should be installed. The LOCI_BASE environment variable should be set to point to the Loci installation directory. The CHEM_BASE environment variable should be set to point to the CHEM installation directory. The installation process follows the standard make, make install procedure.
make
make installFirst the module must be loaded at the top of the vars file. Boundary conditions that permit outflow (e.g. outflow, outflowNRBC, extrapolate, farfield, etc) may be tagged with the sponge tag. A reference flow state along with a length specifying how far from the tagged boundaries the sponge layer is active, and a sponge layer strength can be specified inside the sponge options list.
loadModule: sponge
boundary_conditions: <BC_1=outflow(p=101325 Pa, sponge), ...>
sponge: <p=101325 Pa, T=300 K, u=[100 m/s, 0, 0], length=0.1 m, sigma=50000>