CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

RAS setup for oscillating flow

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 26, 2022, 07:47
Question RAS setup for oscillating flow
  #1
New Member
 
Noah
Join Date: Nov 2020
Location: Germany
Posts: 1
Rep Power: 0
NoahA is on a distinguished road
Hello everybody,

i am currently trying run an transient RANS simulation of an oscillating flow in a simple environment with a structured grid. Unfortunately i am confronted with problems while running the simulation.

The Problem:
The simulation is crashing at around 280-290 seconds. (flow reversing starts at 219.3; oscillating sin period is 438.6). The results until this point are fine, usable and uncompromised.

The Mesh:
The Mesh is a small cylindrical inlet tube into a cylindrical open room with an o-grid setup. The surface of the room, where the inlet tube enters, is treated as a closed wall. All other room surfaces are open. (see attachments)

The Simulation:
I am running an incompressible RAS Simulation with pimpleFoam in PISO mode with 2 correctors, no underrelaxation and the standard kepsilon turbulence model. The maximum Re.-Num. is approx. ~ 2000.

My BC
patch outlet = outlet form the inlet tube into the cylindrical room
patch outletRoom = open surfaces of the room

k
Code:
internalField   uniform 0.015;

boundaryField
{
    inlet
    {
       type 		turbulentIntensityKineticEnergyInlet;
       intensity 	0.1;
       value 		$internalField;
    }
    inletWall
    {
        type 		kqRWallFunction;
        value           $internalField;
    }
    outlet
    {
        type            zeroGradient;
    }
    roomOutlet
    {
        type            zeroGradient;
    }
    roomWall
    {
        type 		kqRWallFunction;
        value           $internalField;
    }
}
epsilon
Code:
internalField   uniform 4.312e-3;

boundaryField
{
    inlet
    {
        type		turbulentMixingLengthDissipationRateInlet;
        mixingLength	0.07;
        value 		$internalField;
    }
    inletWall
    {
        type            epsilonWallFunction;
        value           $internalField;
    }
    outlet
    {
        type            zeroGradient;
    }
    roomOutlet
    {
        type            zeroGradient;
    }
    roomWall
    {
        type            epsilonWallFunction;
        value           $internalField;
    }
}
nut
Code:
internalField   uniform 0;

boundaryField
{
    inlet
    {
        type            calculated;
        value           uniform 0;
    }
    inletWall
    {
    	type            nutkWallFunction;
    	value           $internalField;
    }
    outlet
    {
        type            zeroGradient;
    }
    roomOutlet
    {
        type            zeroGradient;    
    }
    roomWall
    {
        type            nutkWallFunction;
        value           $internalField;
    }
U
  • Inlet with FlowRateInletVelocity with a Sine profile
  • noSlip on Walls
  • zeroGrad at outlets

p
  • totPressure = 0 at outletRoom
  • zeroGrad. everywhere else

-------
Add. Inf.
I've run some laminar sim. with this setup without any Problems. I have as well tried k- and nutLowRe, which did not show any significant differences. I would still be guessing that this is a BC Problem?

I am hoping anybody cloud help me with some advise. Please let me know if add. Information is needed. Thanks in advance.
Noah
Attached Images
File Type: jpg Mesh_Setup.jpg (62.8 KB, 5 views)
File Type: jpg Mesh_inlet.jpg (107.5 KB, 5 views)
File Type: jpg Mesh_O_Grid.jpg (202.1 KB, 5 views)
NoahA is offline   Reply With Quote

Reply

Tags
kepsilon model, oscillating flow, pimple transient, ras incompressible

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Error: Update failed for the setup component in Fluid Flow CFX nudi1001 CFX 4 January 17, 2023 03:01
Review: Reversed flow CRT FLUENT 1 May 7, 2018 05:36
Multiphase flow - incorrect velocity on inlet Mike_Tom CFX 6 September 29, 2016 01:27
[ICEM] Circular 2D Flow Field Setup - Bourke ANSYS Meshing & Geometry 2 December 10, 2015 21:51
Flow Split Setup Question ed FLUENT 1 February 16, 2007 16:55


All times are GMT -4. The time now is 00:32.