# closed tank and dynamic mesh

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 December 1, 2013, 13:27 closed tank and dynamic mesh #1 Super Moderator     Tobias Holzmann Join Date: Oct 2010 Location: Tussenhausen Posts: 2,708 Blog Entries: 6 Rep Power: 51 Hi all, I worked with rhoPimpleDyMFoam some times in non closed cases but now I have a closed volumina. Therefor I got "pcorr" step to 1000 iterations every time. To check if this occure with closed volume cases I changed the tutorial case in the rhoPimpleDyMFoam so that there is no inlet and outlet anymore. Its the same result. pcorr blows up: Code: ```solidBodyMotionFunctions::rotatingMotion::transformation(): Time = 0.0152941 transformation: ((0 0 0) (0.981781 (0 0 0.190014))) AMI: Creating addressing and weights between 10944 source faces and 10944 target faces AMI: Patch source weights min/max/average = 0.945398, 1.00512, 0.999941 AMI: Patch target weights min/max/average = 0.951965, 1.00398, 0.999942 GAMG: Solving for pcorr, Initial residual = 0.999999, Final residual = 20.8413, No Iterations 1000 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0``` Is there any solution? Regards Tobi PS: @admin - if its possible the title can be changed into "closed volume and dynamic mesh"

 December 2, 2013, 06:30 #2 Super Moderator     Tobias Holzmann Join Date: Oct 2010 Location: Tussenhausen Posts: 2,708 Blog Entries: 6 Rep Power: 51 Hi all, I tested my case yesterday again with a few outer faces used to be an atmosphere. Therefor p is totalPressure and U is an pressureInletOutletVelocity. With this Addition the Simulation is running stable and fast. pcorr is normal with a few iterations 5 - 20. But I am still interested why pcorr blows up in closed volume cases. Maybe I should have a look at the equations

 December 8, 2013, 03:25 #3 Senior Member   Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Copenhagen, Denmark Posts: 1,900 Rep Power: 37 Hi Tobias, It sounds to me, as if the compressibility of the fluid is not taken into consideration by the solver/pcorr loop. You probably changed the total volume of the box, and then pcorr has a problem in putting the excess volume somewhere. A suggestion for checking this could be as follows: 1. Set up a simple cavity test. 2a. Move the left and right boundaries with the same velocity. 2b. Move the left and right boundaries with different velocities. Case 2a should be successful, because the total volume remains constant, and 2b should fail. Good luck, Niels __________________ Please note that I do not use the Friend-feature, so do not be offended, if I do not accept a request.

 December 6, 2016, 09:11 #4 New Member   Join Date: Dec 2013 Posts: 11 Rep Power: 12 Hey Tobi. I'm also dealing with a closed domain with moving boundaries. Although my model doesn't blow up, the iterations in the pcorr step are always a lot slowing down terribly the simulations. In your (or others opinion), should a reduced level of convergence for pcorr deteriorate the accuracy of results or can we live with it? Thanks, R

 December 10, 2016, 19:38 #5 Super Moderator     Tobias Holzmann Join Date: Oct 2010 Location: Tussenhausen Posts: 2,708 Blog Entries: 6 Rep Power: 51 I cannot give you any advice but you can check out - or set - the keyword that calculates the pressure correction for closed volumes. You have to add the keyword in the fvSolution file (not sure, check out the sources yourself). Sent from my HTC One mini using CFD Online Forum mobile app __________________ Keep foaming, Tobias Holzmann Last edited by Tobi; December 26, 2016 at 05:25.

 December 16, 2016, 15:51 #6 New Member   Join Date: Jun 2009 Posts: 22 Rep Power: 16 Hi, Have you set a pRef and pRefpoint somewhere in your domain? I can't see that it should be necessary with a compressible solver though. Sent from my iPhone using CFD Online Forum mobile app

 March 27, 2018, 03:26 #7 New Member   MichG Join Date: Nov 2017 Posts: 6 Rep Power: 8 Hello Tobias, I also want to simulate a closed volume stirred tank using the solver rhoPimpleDyMFoam. Im simulating an incompressible fluid, but need the compressible version of the solver for the heat transfer simulation. As you described, the simulation runs only with one patch defined as inletOutlet. My problem is now, because its an inlet, I get a flow in and out of the domain, but I want the domain to be closed. I defined my BC as follow: U Code: ``` oben { type pressureInletOutletVelocity; value uniform (0 0 0); }``` p Code: ``` oben { type totalPressure; p0 \$internalField; U U; phi phi; rho rho; psi none; gamma 1; value \$internalField; }``` Do you know how to define the patch, that I dont get a mass flow in and out of the domain with still getting a stable simulation? Kind regards Michael