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-   -   Difference between MRF and RBM (http://www.cfd-online.com/Forums/star-ccm/96049-difference-between-mrf-rbm.html)

Clerk January 11, 2012 06:06

Difference between MRF and RBM
 
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.

Ladnam January 12, 2012 17:16

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.

sail January 12, 2012 17:56

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 August 12, 2012 22:45

Quote:

Originally Posted by sail (Post 339103)
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

sail August 21, 2012 22:39

Quote:

Originally Posted by saleh alsubari (Post 376721)
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

saleh alsubari August 21, 2012 22:45

Quote:

Originally Posted by sail (Post 378083)
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

abdul099 August 28, 2012 19:49

Quote:

Originally Posted by sail (Post 378083)
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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