Computing Courant number
Hi everyone,
I have one question related to Courant number. I am trying to simulate a flow in a complex channel with icoFoam, and Courant number is giving me some problems. I have info about pressure on both inlet and outlet, but no velocity values are given. Also I have made a tetrahedral mesh and on another stage a hybrid mesh (tetra+prism). In order to satisfy stability criterion based on Courant<1, I am not sure about: 1. Which is delta_x? The maximum edge lenght of tetrahedrons?Minimum? This is an unstructured mesh so delta_x is not fixed! 2. How can I stablish a characteristic velocity magnitude for the formula if I donīt have any info about velocity values? (pressure driven flow) 3. IS there any way of fixing the maximum Courant number (less than 0.75 for example) in all mesh and let OpenFOAM work with time step? Sorry for that stupids questions, but the beginnings are always hard...:eek: Thank you so much in advance! |
First about the mesh: I'm not sure, but I reckon in general a hexaedral mesh should work better than a tetrahedral mesh.
The courant number will be calculated for each cell. I would suggest to just run the solver and have a look at the logfile afterwards. There you can see the mean Courant number and the max Courant number. If it is too high, decrease deltaT or change the mesh. It is also possible to have a look in paraview in which cell the Courant number is too high. See http://www.cfd-online.com/Forums/ope...nt-number.html Regarding question 3. Have a look at the systemDic. There is an entry called "adjustTimeStep". |
All times are GMT -4. The time now is 00:06. |