# Difference between MRF and RBM

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 January 11, 2012, 06:06 Difference between MRF and RBM #1 New Member   Clerk Join Date: Jan 2012 Posts: 1 Rep Power: 0 Hi Everyone, I am new to Star CCM+, What is the difference between moving reference frame and rigid body motion. Except the difference like moving mesh in RBM(unsteady), stationary in MRF(steady).May i know what are all the other difference.

 January 12, 2012, 17:16 #2 Member   Join Date: May 2010 Posts: 38 Rep Power: 8 I will give this a try. In MRF the different bodies are fixed in position but the fluid feels the forces as if the bodies were moving. This will often be good enough for axisymmetric geometry.

 January 12, 2012, 17:56 #3 Senior Member     Vieri Abolaffio Join Date: Jul 2010 Location: Always on the move. Posts: 308 Rep Power: 9 in rigid body motion the reference system stays still, and the domain/flow/mesh is moving. in mrf, as the name suggest, the entire system is moving. because this method is less computationally expensive than the rbm, it is successfully used in, for example, rotating parts, turbiles, isolated propeller analysis (in case of a rotation) saleh alsubari and ank86it like this. __________________ http://www.leadingedge.it/ Naval architecture and CFD consultancy

August 12, 2012, 22:45
#4
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saleh
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Quote:
 Originally Posted by sail in rigid body motion the reference system stays still, and the domain/flow/mesh is moving. in mrf, as the name suggest, the entire system is moving. because this method is less computationally expensive than the rbm, it is successfully used in, for example, rotating parts, turbiles, isolated propeller analysis (in case of a rotation)
hi ...
do u know how to use reference frame in turbine analysis
need to know ,the turbine RPM given the mas flow rate as input

thanx

August 21, 2012, 22:39
#5
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Vieri Abolaffio
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 Originally Posted by saleh alsubari hi ... do u know how to use reference frame in turbine analysis need to know ,the turbine RPM given the mas flow rate as input thanx
sorry to disappoint you, but I belive that to get the rpm you'll need to use the RBM tecnique
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August 21, 2012, 22:45
#6
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saleh
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Quote:
 Originally Posted by sail sorry to disappoint you, but I belive that to get the rpm you'll need to use the RBM tecnique
thanx for replying ...
can u plz elaborate ,about RBM techinqes cuz i have not used that one so far...
thanx a gain

August 28, 2012, 19:49
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Quote:
 Originally Posted by sail sorry to disappoint you, but I belive that to get the rpm you'll need to use the RBM tecnique
I'm sorry I have to disagree. It's just a matter of accuracy and computing time whether to use RBM or MRF. You'll get a (less acurate) result using MRF, but it might still be better than a bad RBM result.
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