|
[Sponsors] |
[OpenFOAM] High pressure range using totalpressure BC |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
February 5, 2019, 11:59 |
High pressure range using totalpressure BC
|
#1 |
New Member
Join Date: Aug 2018
Posts: 12
Rep Power: 7 |
Dear foamers;
I have been trying to understand how pressure works in incompressible flow solvers (PISO in my case) and i found out that pressure in Navier Stokes has no physical meaning but just the gradient. So i tried to find a good BC to couple velocity and pressure and gives me a good results for my project but the pressure in Parafoam makes no sense to me. My BC are as follow; Pressure: Inlet: zerogradient Outlet: totalpressure P0 1.5e5 Gamma 0.0 Value uniform 0 Velocity: Inlet: fixedvalue Value uniform (25 0 0) Outletressureinletoutletvelocity Value uniform(0 0 0) My project is only on an open test section that is symmetric and cst area, you can consider it as a simple jet of air, inflow and outflow. I can't get the pressure to give me a good result, the velocity in the other hand works perfectly if i can say so! The pressure range is so high and has negative values. Since this is incompressible, there are a lot of pressure fluctuations. Can anybody helps me please. I have been trying for months to get this to work. Here are some pictures of what it looks like. One for velocity and the rest pressure. Thankx in advance! |
|
September 10, 2020, 08:54 |
|
#2 |
New Member
Tobias Kienzler
Join Date: Mar 2020
Posts: 13
Rep Power: 6 |
As you mentioned only the pressure gradient is relevant for incompressible solvers, so could just as well set p0 to zero. But more importantly (and what screwed me up for a while) the solver uses kinematic pressure as described at https://www.openfoam.com/documentati...-pressure.html. This means p is not in Pascal but in mē/sē and must be rescaled by rho to actually make sense (and your p0 would have to be divided by rho in return, so 1.5e5 really only makes sense for a density of ca. 1). This rescaling is also relevant in the transportProperties, where nu = mu/rho is used instead of mu!
|
|
Tags |
#fluctuation, #piso, #pressure |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
AMI memory leak? | MichiB | OpenFOAM Programming & Development | 14 | August 1, 2015 18:18 |
High negative pressure with interPhaseChangeFoam | legione | OpenFOAM Running, Solving & CFD | 7 | July 5, 2015 10:28 |
high pressure boundary condition | fragzilla | CFX | 5 | September 14, 2012 02:40 |
Neumann pressure BC and velocity field | Antech | Main CFD Forum | 0 | April 25, 2006 02:15 |
Hydrostatic pressure in 2-phase flow modeling (CFX4.2) | HB &DS | CFX | 0 | January 9, 2000 13:19 |