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1 Study description
In this work, two transient solvers in incompressible viscous flow are compared. One solver is based on the SIMPLE- and the other on the PISO-algorithm. The used solvers are transientSimpleFoam and icoFoam. The original study is included in the .tar.gz-package below, in the doc/-folder.
With icoFoam, a simulation is performed with four different mesh densities. In the transientSimpleFoam computations three parameters are varied: relaxation factor for velocity, the number of SIMPLE-loops and time step length. Each variable gets two different values which results in 8 different parameter combinations in the transientSimpleFoam computations. All eight computations are performed with the same meshes as the icoFoam computations.
The study is made in the spirit of an existing study by Eric Paterson, reference . The flow case, Taylor Green vortex, as well as the Python script used for varying parameters and running OpenFOAM were adopted from his study. For the transientSimpleFoam computations the script needed to be modified. For the modified script, see Section 3
2 Published results
 Turunen, T. "PISO vs. transient SIMPLE: A Comparison of Two Different Transient Solution Algorithms in incompressible CFD with OpenFOAM and Python", BSc thesis, Aalto University, 2011
A PDF copy is included in the uploaded case archive in the folder "doc".
3 How to get the files
The case files are in the following package:
For the simulations you will need:
- funkySetFields, see Contrib_funkySetFields
- Actually, funkySetFields is now part of swak4Foam
- pyFoam, see Contrib_PyFoam
- transientSimpleFoam: transientSimpleFoam.tar.gz
- Or if you prefer from a git repository: transientSimple at wyldckat@github
4 Directory structure
The main directory contains the following files, scripts and directories:
README baseline : baseline case which is cloned using PyFOAM doc : study based on the computations figures : will contain all pictures latex : files needed in creating an appendix with Latex results : contains all computations tools : post-processing tool, plotting scripts and script to create an appendix with Latex runScript.py : runs the computations
 Paterson Eric G., “Python Scripting for Gluing CFD Applications: A Case Study Demonstrating Automation of Grid Generation, Parameter Variation, Flow Simulation, Analysis, and Plotting” , The Pennsylvania State University, The Applied Research Laboratory Technical Report No. TR 09-001, 13 January 2009