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Evaluating mass flow at the domain boundaries
- The aim of this section is calculation of flow through a specified patch.
- We use postProcess utility and functionObject flowRatePatch for summing the flux on patch faces.
- For solvers where the flux is volumetric (i.e. for incompressible solvers)), the flow rate is volumetric; where flux is mass flux (i.e. for compressible solvers), the flow rate is mass flow rate.
- Print help for this utility:
# postProcess -helpUsage: postProcess [OPTIONS] options: -case
specify alternate case directory, default is the cwd -constant include the ‘constant/’ dir in the times list -dict read control dictionary from specified location -field Specify the name of the field to be processed, e.g. U -fields Specify a list of fields to be processed, e.g. ‘(U T p)’ – regular expressions not currently supported -func Specify the name of the functionObject to execute, e.g. Q -funcs Specify the names of the functionObjects to execute, e.g. ‘(Q div(U))’ -latestTime select the latest time -list List the available configured functionObjects -newTimes select the new times -noFunctionObjects do not execute functionObjects -noZero exclude the ‘0/’ dir from the times list -parallel run in parallel -region specify alternative mesh region -roots <(dir1 .. dirN)> slave root directories for distributed running -time comma-separated time ranges – eg, ‘:10,20,40:70,1000:’ -srcDoc display source code in browser -doc display application documentation in browser -help print the usage - The available functionObjects by utility postProcess can be listed by typing # postProcess -list
- In case of steady-state solution we evaluate last time layer only
- Use switch -latestTime
- patchName are inlet and outlet
- Run utility for inlet:
# postProcess -func 'flowRatePatch(name=inlet)' -latestTime - Screen output:
/*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: dev | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : dev-e2ccbbbb Exec : postProcess -func flowRatePatch(name=inlet) -latestTime Date : Jun 16 2017 Time : 12:01:00 Host : $HOSTNAME PID : $ Case : $FOAM_RUN/pitzDaily nProcs : 1 sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10) allowSystemOperations : Allowing user-supplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 287 surfaceFieldValue flowRatePatch(name=inlet): total faces = 30 total area = 2.54e-05 Time = 287 Reading fields: surfaceScalarFields: phi Executing functionObjects surfaceFieldValue flowRatePatch(name=inlet) write: sum(inlet) of phi = -0.000254 End - Same for outlet:
# postProcess -func 'flowRatePatch(name=outlet)' -latestTime - Screen output:
/*---------------------------------------------------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: dev | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ Build : dev-e2ccbbbb Exec : postProcess -func flowRatePatch(name=outlet) -latestTime Date : Jun 16 2017 Time : 12:01:00 Host : $HOSTNAME PID : $ Case : $FOAM_RUN/pitzDaily nProcs : 1 sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 10) allowSystemOperations : Allowing user-supplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create mesh for time = 287 surfaceFieldValue flowRatePatch(name=outlet): total faces = 57 total area = 3.32e-05 Time = 287 Reading fields: surfaceScalarFields: phi Executing functionObjects surfaceFieldValue flowRatePatch(name=outlet) write: sum(outlet) of phi = 0.00025399 End - Resulting flux at the inlet
- Resulting flux at the outlet
