Some useful links about OpenFOAM [Always update]

Fluent Fluent is used for computational fluid dynamics (CFD). Fluent Journal Script A Fluent journal script (e.g. " journalfile.jou ") might look like this: file/read-case-data aircraft.cas it 1000 wd "aircraft.dat" Submitting a Batch Fluent Job to Slurm With the correct journal file set up, the final step is to submit this to the Slurm queuing system. #!/bin/sh #SBATCH -n 1 # 1 core #SBATCH -t 1-03:00:00 # 1 day and 3 hours #SBATCH -p compute # parition name #SBATCH -J fluent_batch # sensible name for the job # load the relevant module files. NB: if unsure about # what you need, please contact ops source /etc/profile.d/modules.sh module load apps fluent # run slurm in batch on the allocated node(s) # the '-t4' specifies 4 cores (academic licensing) fluent 2d -g -t4 -i journalfile.jou > outputfile.out The fluent options in the above Slurm script are: 2d the fluent version used -g no graphical environment -i journ

yPlus utility in OpenFOAM

May 02, 2017

This post is about how to calculate yPlus in OpenFOAM. For RANS Note that yPlusRAS calculates y* and not y+ 1. With wall function; · type ‘yPlusRAS’ for incompressible flow · type ‘yPlusRAS’ –compressible for compressible flow 2. Without wall function; · type wallShearStress if it is incompressible. If not, add " -compressible " flag · calculate manually: sqrt(wallShearStress/rho) * y/nu y = the distance to first cell from the wall nu = kinematic viscosity Be careful: You should use the cell center (height of the cell devided by two) for y For LES type ‘ yPlusLES’ Note: Y-star = rho*Cmu^0.25*sqrt(k)*y/mu y-plus = rho*sqrt(tau_w/rho_w)*y/mu Y-star is related to the turbulent kinetic energy and y-plus to the wall shear stress. Where is the friction velocity at the nearest wall, is the distance to the nearest wall and is the local kinematic viscosity of the fluid. is often refered to

wallShearStress in OpenFOAM

May 08, 2017

The wall shear stress, , is given by: Where is the dynamic viscosity, is the flow velocity parallel to the wall and is the distance to the wall. The SI unit of wall shear stress is pascal ( ), which is identical to . The skin friction coefficient, , is defined by: Where is the local wall shear stress , is the fluid density and is the free-stream velocity (usually taken ouside of the boundary layer or at the inlet). Incompressible Flow Laminar In OpenFOAM, wallShearStress usually is in "kinematic pressure", namely in "m2/s2". It doesn't take into account the density of the fluid. So, you should multiply by rho to reach tau. tau = (wallShearStress) * rho or with wallGradU utility tau = (wallGradU) * mu You can use the Calculator filter in ParaView to multiply the "wallShearStress" field by the density value. Turbulence Compressible Flow You must run "wallShearSress -compressible&qu

Search This Blog

About CFD