CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FloEFD, FloWorks & FloTHERM

Solidworks Flow simulation Boundary condition question [image included]

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 22, 2012, 17:03
Default Solidworks Flow simulation Boundary condition question [image included]
  #1
New Member
 
Diego
Join Date: Jul 2012
Posts: 3
Rep Power: 5
diego11 is on a distinguished road
Hey everyone,

I need some help with the boundary conditions of this problem. The water tank you see here has some jets on the inside corners (highlighted yellow) and along some of the walls. each one of the jet should shoot water into the tank at 4.6 m/s. I think I got that one...





But, I need a volume flow rate on these floor drains that should be releasing 40% of the volume as an outlet. There will be other drains that release 60% of the volume.

When I try to do this, it requests a pressure outlet, though.

can you guys help me set up the boundary conditions on this?

Also, the top lid of the tank is required for the solidworks flow simulation but it will actually be open to air and shouldn't ever overflow. is there a boundary condition I should be putting on this?

Thanks so much everybody!

edit: also, what goals should i be putting on this problem? trying to find the velocity of water in the tank at several points, but i think vectors/contours will tell me that after anyway
diego11 is offline   Reply With Quote

Old   August 6, 2012, 02:52
Default
  #2
Senior Member
 
Boris Marovic
Join Date: Jul 2009
Posts: 378
Rep Power: 12
Boris_M is on a distinguished road
Hi Diego,
the problem you are trying to solve is hard to solve with SW Flow Simulation. It is a free surface flow you are trying to solve. For some of these tasks you can simplify the model just like you did with the lid on top fixing a fluid surface. But with the requested boundary conditions you have it doesn't work as SWFS needs to have either at least two pressure openings or at least one pressure and one flow rate openings. With two flow rate openings you have not defined a pressure and therefore it cannot be solved. The initial condition settings with pressure do not define where the pressure lies, with a pressure boundary condition a specific pressure is defined at a certain location and the pressure distribution can be calculated.

Where do you get your velocity from or the outlet volume flow?
If you have another opening that takes 60% of the volume flow rate then why not define a pressure boundary condition there and a volume flow rate condition to the 40% opeing. then you have at least one pressure opeing and since the mass balance has the be fulfilled it will be by pushing in a certain mass through the pipes and sucking out a certain mass through the one opening and the rest goes through the other opening.

I hope this helps,
Boris
Boris_M is offline   Reply With Quote

Old   August 7, 2012, 15:44
Default
  #3
New Member
 
Diego
Join Date: Jul 2012
Posts: 3
Rep Power: 5
diego11 is on a distinguished road
Boris,

Thank you so much for reaching out. On this problem, I did just that:

I put an ideal lid on the top. I placed a pressure outlet on the center drains that are on the floor and on another outlet I placed a 60% mass flow boundary condition.

those inlet jets remained as a velocity inlet.

In the surface goals, i placed a mass flow goal on the center drain and in fact did see 40% of the flow leaving that drain.

I'm not sure if the pressure gradients solved by SWFS were correct. Thanks again for your help. Is this approach similar to the one you described?

p.s. - If anyone has any advice on this one, I'm happy to hear it and run a new simulation.
diego11 is offline   Reply With Quote

Old   August 8, 2012, 02:26
Default
  #4
Senior Member
 
Boris Marovic
Join Date: Jul 2009
Posts: 378
Rep Power: 12
Boris_M is on a distinguished road
Hi Diego,
that's exactly what I meant. You could also run a simulation where you define the mass flow rate on the 40% opening and the pressure opening on the 60% so you can see a difference on the simulation results that may occure due to forcing a suction boundary condition on the one outlet but not on the other.

It is hard to say if the pressure field is good as the software is not really capable of doing such free flow/free surface flows. So this is just an aproximation.

Boris
Boris_M is offline   Reply With Quote

Reply

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
Boundary condition setting regarding turbine simulation using CFX Lacerlacer CFX 11 March 12, 2012 10:32
Simulation of a complex wing in solidworks flow simulation niels1900 FloEFD, FloWorks & FloTHERM 6 April 20, 2011 10:44
Boundary Condition definition for Tensorial Fields and viscoelastic flow simulation titio OpenFOAM Running, Solving & CFD 1 February 4, 2009 10:14
Airfoil boundary condition Frank Main CFD Forum 1 April 21, 2008 18:36
Boundary condition for not fully-developed flow John FLUENT 0 July 15, 2005 07:07


All times are GMT -4. The time now is 22:10.