CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Flowrate at inlet and outlet not balancing ( centrifugal pump ) -- pimpleDyMFoam

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

Like Tree3Likes

LinkBack Thread Tools Search this Thread Display Modes
Old   November 25, 2015, 05:33
Sravan Kumar
Join Date: May 2014
Posts: 57
Rep Power: 10
coolcrasher is on a distinguished road
Hi all,

Last month we have tried running the simulations with 3 different meshes and also with different timesteps. I have attached the excel sheet which has the results.

We have seen that using movingWall velocity boundary condition on the patches which are rotating give meaningful results and also we have used the same boundary conditions for others as used in propeller tutorial. ( for pressure, k, omega, nut. KomegaSST Turb model is used ).

Three different meshes are as follows
1) Basic mesh ( which has been used previously )
2) Finer mesh ( Basic Mesh is taken, mesh at all regions except AMI patches are made finer )
3) Finer AMI mesh ( Finer Mesh is taken, mesh at AMI patches are made much finer )

Following are the observations found:
1) We still observe the flowrate difference between the AMI patches.
2) Flowrate difference is less in case of Finer AMI mesh compared to Basic Mesh. That means that as we refine the AMI patches further we observe that the flowrate error is reducing for a particular timestep.
3) For a type of Mesh we observe that as we get no flowrate difference between the AMI patches at a bigger timestep ( like 1e-2 ) but as we make the time step smaller ( till 1e-5 ) we observe that the error is gradually increasing. ( which is quite strange, we expect to get better results as we take finer time steps ).

We have tried running the Basic case with time step of 1e-4 with k epsilon model. It has ran fine till first few time-steps ( around 2-3 revs of impeller ). Then the case has diverged and crashed. But even during that time we have observed the loss in flowrate.

The problem of flowrate mismatch has not been solved yet. Also we are confused what is causing this error. Is it due to bug in OpenFoam or due to some wrong boundary conditions used.

Please help me with this regard.
Attached Files
File Type: xls MeshStudy.xls (9.0 KB, 3 views)
coolcrasher is offline   Reply With Quote


ami, pimpledymfoam, pump, transient

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
Calculate Mass Flowrate and Mass Flow Averaged Total Pressure at inlet and outlet coolcrasher OpenFOAM Post-Processing 7 November 4, 2021 04:57
Want Impeller Driven Fluid Flow: What Inlet and Outlet BC to use for Centrifugal Pump Zev Xavier FLUENT 3 May 9, 2016 06:42
pump outlet pressure higher than inlet pressure jstan3 FLUENT 14 February 13, 2014 23:44
Problem with centrifugal pump calculation Michiel Main CFD Forum 2 June 17, 2012 21:32
inlet and outlet boundary condition of pump Thammasak CFX 0 February 9, 2004 13:02

All times are GMT -4. The time now is 00:19.