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#1 |
Guest
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I would like to see hydrostatic pressure distribution in STAR-CD.
Also when I run simple vertical pipe case in STAR-CD, I define top as Inlet and bottom as outlet. I specify V velocity which is -2 m/s and gravrity in Y direction with -1 in gravity features of STAR-CD. But I get the same results, if I run with gravity or without gravity in STAR-CD. Does STAR-CD take into account gravity in single phase flow? I know that STAR-CD take into account gravity for VOF means free surface flow with air and water. Please kindly clarify my belief. Thanking you in advance, Sachin |
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#2 |
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You need to turn density to something other than constant and activate buoyancy
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#3 |
Guest
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Thanks for the reply. I will turn density to non constant option. And it may also helo me to actiave buoyancy, because before when I tried to actvate buoyancy it shows buoyancy can not be turned on for constant density.
I will keep you updated. Regards, Sachin |
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#4 |
Guest
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Actually you can see the difference even without buoyancy and variable density - plot static pressure instead of piezo
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#5 |
Guest
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About plotting static pressure and piezometric pressure, I got exactly same values uoto all decimal places. STAR-CD manual says that piezoetric pressure= static pressure - (density*gravity*height).
But I got the same graphs, similar post registres, if I compare piezo Vs. static pressure, which is surprising and illogical. Doest STAR-CD take into account gravity for single phase incompressible flow? Thanks . |
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#6 |
Guest
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yes, STAR-CD take into account gravity for single phase incompressible flow
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#7 |
Guest
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Hi Thanks for the reply.
How can I see effect of gravity in STAR-CD for single phase incompressible flow? I tried to do it by yself. I turned on gravity and then turned off, I got same results, which looks pretty surprising. I set gravity in Y direction with x=0, y=-1, and z=0 with g=9.8066 m/s2. But I can not turn on buoyancy for single phase incompresssible flow, as it says that Buoyancy can not be turned on for constatnt density. Am I setting up problem correctly or I have to do anything else to see effect of gravity? Thanks for reading my long probelm. Sachin |
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#8 |
Guest
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Your question really puzzled me. I've checked it too, and you're right - no difference!
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#9 |
Guest
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Well, according to the manuals gravity is taken to the account only for free-surface and buoyancy problems.
Though I can't imagine right now an incompressible problem where gravity induced pressure gradients will be important, this neglection of gravity will at least require additional steps in post processing if you want REAL static pressure. If my memory serves me right, the behavior was different in v3.15, i.e. plotting pressure and static pressure was giving different pictures. But I think for incompressible flows it was merely a post-processing option. |
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#10 |
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Hello,
I have got the same problem while trying to sediment solid phase (5%, Eulerian treatment) in a closed volume of static fluid: there is no gravity there ![]() Best regards, Boris |
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#11 |
Guest
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Hi To the best of my knowledge gravity is not taken into account in STAR-CD unless it is free surface problem. Any comments / suggestions are welcome
Sachin |
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Thread | Thread Starter | Forum | Replies | Last Post |
Set gravity in UDF | Ray Hong | FLUENT | 1 | August 6, 2009 09:05 |
Gravity in STAR-CD | Sachin | Siemens | 1 | March 8, 2008 10:20 |
gravity-table.scm scheme file for trans gravity | Shankar | FLUENT | 0 | May 31, 2006 04:30 |
Specifying gravity | KHALID | FLUENT | 0 | November 6, 2005 02:28 |