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-   -   Comparing Unscaled Continuity Residual with an appropriate scale (http://www.cfd-online.com/Forums/fluent/102677-comparing-unscaled-continuity-residual-appropriate-scale.html)

sagila May 31, 2012 08:01

Comparing Unscaled Continuity Residual with an appropriate scale
 
Hello,


In FLUENT User Guide, in the section of "Judging Convergence", it is mentioned that:
If you make a good initial guess of the flow field, the initial continuity residual may be very small leading to a large scaled residual for the continuity equation. In such a situation it is useful to examine the unscaled residual and compare it with an appropriate scale, such as the mass flow rate at the inlet.

Is there anybody who could help me understand what it means by examining the unscaled residual and comparing it with an appropriate scale, such as the mass flow rate at the inlet?


For instance, in my case that I am simulating with FLUENT:
unscaled continuity residual = 0.005,
mass flow rate at inlet = 0.024068371 kg/s,
mass flow rate at outlet = 0.024068366 kg/s,
net flux imbalance of mass flow rate = 5e-9.


Thanks.
Best Regards,
Sagila


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