|
[Sponsors] |
![]() |
![]() |
#1 |
New Member
Join Date: Aug 2022
Location: Czech Republic
Posts: 7
Rep Power: 4 ![]() |
Hello,
I need help with decision about which evaluation method to use for determining preassure drop. I run transient, incompressible, k-Omega sim of pipes (with multiple curves, shape changes etc.) to compare old/new geometry. I found two ways to evaluate pressure loss (using Paraview): a) integrate variables on inlet, gained pressure on inlet equals pressure drop
I expected to these values be the same, but... Values are different (for example a) 450 Pa, b) 800 Pa ). After comparing old vs new state of pipes, improvement is observed in both cases but different (method a) 30% b) 60% of original pressure loss). My question is, how to choose whitch method should be trusted? Thanks a lot for help. pressureloss.PNG Picture of original pipe geometry (green point is location of found max pressure) |
|
![]() |
![]() |
![]() |
![]() |
#2 |
Senior Member
Join Date: Apr 2020
Location: UK
Posts: 711
Rep Power: 14 ![]() |
If I follow your posting correctly, for method b you are using ParaView to find the maximum P (Pmax) in the domain, and then I assume that you have a fixedValue pressure boundary at the outlet, with p=0, so you are assuming that the pressure loss is equal to Pmax? Well that method will not be very accurate since the pressure can rise above the inlet pressure in a stagnation area.
A better approach would be to get the solver to calculate the area-averaged pressure on the inlet and outlet boundaries. You can do this with a function object either during the run or after the run. Check out the following, for example: https://cpp.openfoam.org/v8/classFoa...e.html#details PS are you remembering that the pressure in the incompressible solvers is typically kinematic, i.e. p/rho? |
|
![]() |
![]() |
![]() |
![]() |
#3 |
New Member
Join Date: Aug 2022
Location: Czech Republic
Posts: 7
Rep Power: 4 ![]() |
Hi, thanks for reply.
My problem is, that I am not skilled in programming, and thus I use Helyx OS (GUI for OpenFOAM). As you said, method of averaging pressure on inlet/outlet should do this, and I think that it should be similar as "integrate variables" in Paraview (method a) ) - dont you think? (yes, I am aware of kinematic pressure ![]() |
|
![]() |
![]() |
![]() |
![]() |
#4 | |
Senior Member
Josh Williams
Join Date: Feb 2021
Location: Scotland
Posts: 113
Rep Power: 5 ![]() |
Quote:
|
||
![]() |
![]() |
![]() |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
static vs. total pressure | auf dem feld | FLUENT | 17 | February 26, 2016 13:04 |
Outlet pressure | aja1345 | FLUENT | 5 | August 18, 2015 11:02 |
sonicFoam - pressure driven pipe: flow continuity violation and waveTransmissive BC | Endel | OpenFOAM Running, Solving & CFD | 3 | September 11, 2014 16:29 |
Setting up the pressure variation due to tornado in a duct(UDF)+animation | guillaume1990 | FLUENT | 0 | March 3, 2014 11:59 |
Gas pressure question | Dan Moskal | Main CFD Forum | 0 | October 24, 2002 22:02 |