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April 2, 2019, 10:53 
How to check the results of OpenFOAM Solver?

#1 
Member
Priyanka P
Join Date: Apr 2019
Location: Germany
Posts: 40
Rep Power: 7 
Hello Everyone,
I am new to OpenFOAM and CFD. However, I have been reading about OpenFOAM and basics of CFD from a while now. I know the flow of solving a case in OpenFOAM which starts from making a geometry, then mesh and then solving it using a solver. What I don't understand is, 1. How do we know that the solver has already solved my problem? 2. Where can I see the parameters changing? 3. I read that we know our problem is solved when solver converges. How can I check that the solver has converged already? I have tried to understand the log which is generated by the solver but could really understand what it is happening inside it. 

April 3, 2019, 05:53 

#2  
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Robert
Join Date: May 2015
Location: Bremen, GER
Posts: 292
Rep Power: 12 
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Code:
Time = 19999 smoothSolver: Solving for Ux, Initial residual = 0.00476975, Final residual = 8.58411e09, No Iterations 36 smoothSolver: Solving for Uz, Initial residual = 0.0665207, Final residual = 9.32058e09, No Iterations 42 [...] GAMG: Solving for p, Initial residual = 0.115453, Final residual = 8.04117e09, No Iterations 39 [...] ExecutionTime = 566.98 s ClockTime = 577 s Init. res.: Residual value at the beginning of the timestep. Final res.: Residual value at the beginning of the timestep. If the final residual falls below the residualControl value your simulation end. ExecutionTime is the time spend by your computer actually doing something and ClockTime being the time since you started your simulation. You can also use runtime postprocessing by including #includeFunc residuals in your control dict. This will write a file with all residuals for every timestep, which then can be plotted during runtime using the foamMonitor utility. As such you can graphically observe your residuals decreasing.
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April 5, 2019, 08:38 

#3 
Member
Priyanka P
Join Date: Apr 2019
Location: Germany
Posts: 40
Rep Power: 7 
Hello RobertHB,
Thanks a lot for your reply, it cleared many of my doubts. I was trying to understand the physics behind the calculations. Now my question is: Is it possible to verify a simple hand calculated problem on OpenFOAM.For example, I want to realise the heat transfer in a metal rod attached by an aluminium plate on both sides. I know the temperature of both plates. So, can I realise this case in OpenFOAM? If yes, do I get the value of heat flow rate in the log file? Please excuse me if it was a silly question. Thank you 

April 8, 2019, 03:18 

#4  
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Robert
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