|
[Sponsors] |
coding a steady multiphase solver twophaseeulerfoam |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
October 13, 2011, 13:16 |
coding a steady multiphase solver twophaseeulerfoam
|
#1 |
Member
Miles
Join Date: Sep 2011
Posts: 48
Rep Power: 15 |
Hi,
I am using the twophaseeeulerfoam solver to simulate air bubbles in water. I want to have a steady state version of the solver. Solution1 According to what I have read, I should first try to under-relax the resolution and raise the time step. I do not understand why? In fact I do not understand the role of under-relaxtion factor in an unsteady solver. Does anyone have a point on the subject or some documentation of the relaxation process in Openfoam (and in general, reading is never bad!)? This could help me to understand. Solution2 On the other hand if I want to change the solver to be steady witch library I was thinking to do so - Remove time dependence in the solver - Change the vel-press scheme (I was thinking using simple scheme) - Modify the fvsol and fvscheme dict. Does this seem correct? Does this seem an affordable task for an OF newbee? Thanks for your opinions and help. Regards, |
|
October 13, 2011, 13:16 |
|
#2 |
Member
Miles
Join Date: Sep 2011
Posts: 48
Rep Power: 15 |
Hi
I have tried the first solution but it seems that putting a subdict for relaxation at the end of fvSolution has no effect. I am not sure if it is taken into account. So I switched to the coding of a steady twophaseeluerfoam solver. I am tryning to understand how the solver is coded. I have a few questions and my sorry in advance if it seems to easy but my C++ is very bad. 1.fvVectorMatrix UbEqn(Ub, Ub.dimensions()*dimVol/dimTime) Is it possible to modify the definition of fvVectorMatrix like that: fvVectorMatrix UbEqn(Ub, Ub.dimensions())
What is the definition and the purpose of rUaA and UaEqn.A() ? Is this related to the first guess on momentum equation in the PIMPLE algorithm?
4. DDTU.h What is the purpose of having a special file for the equation on UA and UB? Can it be included in my SIMPLE loop -since I will move the scheme from pimple to simple. Thanks for any help. Regards, |
|
October 14, 2011, 20:52 |
|
#3 |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Just a suggestion: do not post the same message multiple times, or you won't receive any answer.
Best, Alberto
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
|
October 15, 2011, 19:45 |
|
#4 |
Member
Miles
Join Date: Sep 2011
Posts: 48
Rep Power: 15 |
Sorry for that
That was not my intention. I wanted to move the thread to the proper section and delete the older. But I did'nt manage to find how to delete a thread... orry again. Miles |
|
October 15, 2011, 19:49 |
|
#5 | |
Senior Member
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,912
Rep Power: 36 |
Quote:
I don't know if it's possible to delete a thread without administrative rights. :-?
__________________
Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. |
||
June 7, 2016, 06:03 |
|
#6 |
New Member
gned
Join Date: Oct 2012
Posts: 18
Rep Power: 13 |
dear Alberto,
as you expert of multiphase flows, if i have this case with, let's take, very simple geometry as a common pitzDaily nozzle with incompressible flow inside but which then really separates at the sharp corner so that, contrary to this usual picture where after the corner a vortex filled of liquid forms, we have really a void not-wetted stagnant zone. https://www.dropbox.com/s/8g5lsjydba2nhk0/pitz.png?dl=0 As the free-surface (in corrispondence of which we have a sharp change into the fluid density from rho to 0) detaching is unknown a priori, which solver to use in OF to find the solution? An incompressible solver will put at best, at the beginning, a stagnant pocket there but of fluid, and so unstable because with time this zone wil be filled with vorticity (also I find absolute negative pressure inside it). A compressible solver would solve an equation of state at the dead zone but actually rho=0 there (I fear to have continuity problems). So an interFoam maybe with a rho -> 0 (indeed I would like to find the solution with still no cavitation occurs, i.e. with the dead zone not still vapour-filled through an interPhase ChangeFoam but really void enveloped by separated flow) ? Or I must program some changes in a solver, what you suggest ? Thank you really much |
|
February 6, 2019, 16:25 |
Converting twoPhaseEulerFoam into steady state solver using fvoptions
|
#7 |
Member
Join Date: Apr 2016
Posts: 30
Rep Power: 10 |
Hi all,
I have been following this thread and I would like to ask if there is another way to convert twoPhaseEulerFoam into a steady state solver. fvSchemes has a option called ddt schemes. Code:
ddtSchemes { default steadyState; } Thanks and Regards, Shantanu |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
convergence issues on steady state solver | icemaniac178 | CFX | 1 | March 30, 2011 19:11 |
time step and iterations in steady state problem using transient solver | jing113cn | FLUENT | 2 | January 15, 2010 03:18 |
Steady state solver for chemical reaction | hamburgFoam | OpenFOAM Running, Solving & CFD | 2 | January 8, 2010 08:34 |
Looking for a steady state supersonic solver | achilleslaststand | OpenFOAM Running, Solving & CFD | 0 | December 20, 2009 09:23 |
steady state and multiphase... | ben | Phoenics | 5 | April 25, 2003 05:48 |