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No rating yet Subject: Re: FLOTRAN liquid under inertial loading Author: Mark Troscinski Date: 2008-05-06 05:29:24Hi Ian,
If you use the ACEL command to impose a global acceleration body force on a FLUID141 or FLUID142 element model, momentum will be imparted to the fluid only if the energy equation is included in the solution and density gradients, like those occurring in natural convection applications, are present.
A possible workaround for your problem would involve imposing nodal body force densities via the BF command and the FORC label.
Best regards,
Belcan Corporation's ANSYS Group is now SimuTech Group - Chicago.
- Please note my new e-mail address.
Mark Troscinski Senior Engineering Analyst SimuTech Group - Chicago 209 Camelford Road McMurray, PA 15317 mtroscinski_at_SimuTechGroup.com 724-747-7476
________________________________________ From: xansys-bounces_at_xansys.org [xansys-bounces_at_xansys.org] On Behalf Of Prentice, Ian (GE Infra, Aviation, US) [ian.prentice_at_ge.com] Sent: Monday, May 05, 2008 1:49 PM To: ANSYS User Discussion List Subject: [Xansys] FLOTRAN liquid under inertial loading
I am attempting what I thought would be a very simple FSI using FLOTRAN. I have no CFD background, but have considerable experience in structural analysis using ANSYS, I understand FLOTRAN is rather outdated, but chose it as the tutorial FSI example looked simple, and I am familiar with the Classic interface. Of course no one else here uses it! I want to look at the behavior of a hollow metal object submerged in fluid under gravitational acceleration, and rotational inertia. As such I need the fluid to develop a pressure gradient under the inertial loads, and then apply the pressure to the surface of the submerged object. I have not got very far, I cannot even get the liquid to develop a pressure under gravitational loads. Imagine a stationary vertical pipe full of water, the pressure at the bottom is rho.g.h, simple enough. It has been suggested to me that FLOTRAN cannot solve this type of problem as there is no flow and no density change, but I thought I should check on the list before giving up. I think this is more likely to be rookie mistake. I have also tried using the fluid79 contained fluid element which demonstrated the effect I am looking for, but suffers extreme mesh distortion with the amount of relative motion I am looking for. Thanks for any help, Ian Prentice GE Aircraft Engines Evendale Ohio
/PREP7 ET,1,FLUID141 RECTNG,0,2*12,0,20*12 LESIZE,ALL,2,,,1,0 NSEL,S,EXT D,ALL,,,,,,VX,VY NSEL,ALL ESEL,ALL ! FLDATA2,ITER,EXEC,200 FLDATA2,ITER,OVER,50 FLDATA5,OUTP,SUMF,50 ! flda,pres,refe,14.7 !flda,bbulk,beta,300e4 flda,temp,nomi,70 flda,temp,ttot,70 flda,temp,bulk,70 toff,460 ! flda,prot,dens,liquid flda,prot,visc,constant flda,nomi,dens,.0324/386.4 flda,nomi,visc,2.6e-5 !* ACEL,0,386.4,0 FLDATA18,METH,PRES,1 FLDATA19,TDMA,PRES,100 FINISH /SOLU SOLVE FINISH /POST1 SET,LAST plns,pres ^-------------------------------------------------------- | XANSYS - www.xansys.org | | The Discussion List for users of ANSYS, Inc. Software | | Hosted by PADT - www.padtinc.com | ^-------------------------------------------------------- ^-------------------------------------------------------- | XANSYS - www.xansys.org | | The Discussion List for users of ANSYS, Inc. Software | | Hosted by PADT - www.padtinc.com | ^--------------------------------------------------------