CFD Online Logo CFD Online URL
Home > Forums > FloEFD, FloWorks & FloTHERM

Urgent Please: is this a flow simulation error?

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

LinkBack Thread Tools Display Modes
Old   August 13, 2012, 22:03
Default Urgent Please: is this a flow simulation error?
New Member
Join Date: Jul 2012
Posts: 3
Rep Power: 5
diego11 is on a distinguished road
Urgent Please: Is this a Solidworks error? velocity inlet doesn't match up with volume flow rate goal

This question is Not Answered.(Mark as assumed answered)
Hey guys...

I've been getting this error and I want to know how to get past it, it's a simple setup:

i have a hollowed pipe so a circular inlet and i've put some lids on either side:

inlet BC: 1 m/s
inlet Area: 1 m^2

you'd think this would give me a volumetric flow rate into the pipe of 1 m^3/s, but no.. see the surface goals i have below:

Goal Name UnitValue Averaged Value \
SG Volume Flow Rate outlet[m^3/s] -3.987011588 -3.987011588SG
Volume Flow Rate inlet[m^3/s] 3.987011588 3.987011588SG
Av Velocity outlet[m/s] 1.000000904 1.000000813SG
Av Velocity inlet[m/s] 1 1

Can someone please help me out? I need to validate this model by tomorrow

p.s. - This was done in SW2012 if that matters
diego11 is offline   Reply With Quote

Old   August 17, 2012, 11:05
Senior Member
Boris Marovic
Join Date: Jul 2009
Posts: 416
Rep Power: 13
Boris_M is on a distinguished road
Hi Diego,
sorry for the late reply, but do you have an image of the model in a section view and the mesh at the inlet so I can see how good the mesh is?
Please use the "use CAD geometry" setting in the cut plot switched off for this screenshot. This shows you the real mesh that is used for the solver, with that option enabled it gives your nicer images, it's not wrong but not the best way to analyse the mesh quality.

I assume the mesh resolution on the surface is not accurate. If the mesh is good you should see around 1m^3 volume flow rate simply because 1m*1m^2 should not be much higher except if the represented surface is not as big as it should be.
You can check that with the surface parameters at this inlet and check for the "CAD Fluid Area" and "Surface Area". They shouldn't have a too big difference. Since you use 1m/s as BC you can already see the surface should be the the same value. The difference between these two surface values is due to the surface approximation of the mesh and should be very small if the mesh is good.

I hope this helps,
Boris_M is offline   Reply With Quote

Old   September 1, 2012, 09:44
New Member
Joe Galliera
Join Date: Aug 2012
Location: Vermont
Posts: 4
Rep Power: 5
flowjoe is on a distinguished road
Send a message via Skype™ to flowjoe
The flowrates that you are calculating are too close to 4 to not ignore the fact that your geometry may be incorrectly defined. (The velocity is good, the flowrate in matches out so everything else is good.) Remember that Area equals pi*D^2/4; you might be forgetting to divide by 4. The diameter for an Area of 1 m^2 should be approx. 1.12838 m.
flowjoe is offline   Reply With Quote


Thread Tools
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 On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Saving ParaFoam views and case sail OpenFOAM Paraview & paraFoam 9 November 25, 2011 16:46
Version 15 on Mac OS X gschaider OpenFOAM Installation 120 December 2, 2009 11:23
error while running paraFoam! padmanathan OpenFOAM 9 October 13, 2009 05:17
Installation OF1.5-dev ttdtud OpenFOAM Installation 46 May 5, 2009 02:32
attach/detach (valve opening/closing) phsieh2005 OpenFOAM Running, Solving & CFD 2 March 21, 2009 06:18

All times are GMT -4. The time now is 03:48.