[Anouk]

Dear OpenFOAM Users,


for a long time I'm searching for a way to visualise the residuals as a field. Does anyone know a quick way to extract the residuals at all grid points (as a field)? Or at least how to extract the location at which the residuals attain their maximum values?

Background: I want to see where the maximum residuals occur in case of convergence problems. If I could get the residuals as field or the location of the maximum residual this would be of great help.


Best wishes,


Anouk

[yambanshee]

Writing residuals is a feature introduced in OF1806 and is demonstrated here: https://www.openfoam.com/releases/op...esidual-fields

You can see it's usage by following one of these two tutorials:
$FOAM_TUTORIALS/heatTransfer/buoyantBoussinesqPimpleFoam/BernardCells/system/residuals
$FOAM_TUTORIALS/incompressible/pisoFoam/LES/motorBike/motorBike/system/stabilizationSchemes

[Anouk]

Thank you for your reply yambanshee.


I've tried the solution you proposed. If I use the residuals utility (i.e. using #includeFunc residuals in the controlDict), a residuals.dat file is generated (in the postProcessing folder). This file only contains the maximum(?) of the initial residual of a certain field at a certain time. However, what I need is the (initial) residual as a field or at least not only the maximum (initial) residual, but also its location.



The website you suggested shows that it's possible to obtain the initial residual as a field. However, the examples shown do not explain how. Could you please explain?


Btw, the second tutorial does not even exist in my OpenFOAM version (5/6/7 from openfoam.org)...

[GerhardHolzinger]

Originally Posted by Anouk

Btw, the second tutorial does not even exist in my OpenFOAM version (5/6/7 from openfoam.org)...

That's because the OpenFOAM releases from the OpenFOAM Foundation and from ESI/OpenCFD are two separate, distinct releases. Thus, there will be certain cases/solvers/models which are present in one release, that are missing in the other one.

However, since the split between the releases from the OpenFOAM Foundation and ESI/OpenCFD is quite recent, it is possible to port models and solvers from one release to the other. Sometimes, it's even quite straight forward.