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simpleFoam-MRF to rhoSimpleFoam-MRF strange results

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Old   September 17, 2019, 11:00
Default simpleFoam-MRF to rhoSimpleFoam-MRF strange results
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Kmeti Rao
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Hello Foamers,

I am simulating a propeller which I have described in the following link One half propeller simulation with MRFSimpleFoam crashing. Thanks to all users who have helped me to come to this point with the simulation, starting from full propeller configuration to half propeller configuration, with so many inputs in-between.

The results obtained so far are satisfactory and now I am continuing this simulation by considering the compressible effects, as I am willing to increase the motor rpm in future.

A brief introduction with the setup: I am using OpenFOAM 6 from openfoam.org, I have prepared the initial setup of incompressible steady state simulation with MRF, using different tutorials available(pimple --> propeller and simple --> mixer vessel) and inputs from the forum. Now I have switched to rhoSimpleFoam by editing the p file and adding alphaT and T to the latest time step.

The following are my results obtained during the simulations involving simpleFoam and rhoSimpleFoam, as it can be seen, both the results are almost similar except the highlighted one. The force in x-direction has been drastically increased, while the area of interest i.e., the thrust and torque in the z-direction are satisfactory. It would be great if anyone explains why this strange behavior could happen. Also let me know if I need to provide more information regarding setup such as ICs and BCs, if it is a complex error.

Quote:
sum of forces:
pressure : (0.291062 3.70328 22.952)
viscous : (0.000151899 0.251535 -0.0315308)
porous : (0 0 0)
sum of moments:
pressure : (-0.0905238 5.44235 -0.793572)
viscous : (-0.00136577 -0.00609683 -0.0587384)
porous : (0 0 0)
After initializing the compressible simulation by reconstructing the last step of the in-compressible simulation, and the results obtained are,

Quote:
sum of forces:
pressure : (322.763 3.51019 21.65)
viscous : (0.000227725 0.296663 -0.04378)
porous : (0 0 0)
sum of moments:
pressure : (-0.0807525 5.15715 -0.74892)
viscous : (-0.00126643 -0.00468166 -0.0614343)
porous : (0 0 0)
Thank you all in advance,

Krao
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Tags
compressible flow, forces and force coeff., propeller, rhosimplefoam

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