[sthavishtha]

Dear Dr. Mathias

Thanks for the comments.

The error arises due to the compiler version. I now use GCC 6.2.0 and it works. Using an old compiler version (GCC 5.2.0) earlier was enough to compile cavity2d, cylinder2d, cylinder3d problems. So, I was unable to identify the issue earlier with the examples available in the particles/ folder.

Regards
Sthavishtha

[sthavishtha]

Dear Dr. Mathias

I forgot to mention in my earlier post. I did try with a generic BUILDTYPE as well. Yet, I get the same error.

Regards
Sthavishtha

[sthavishtha]

A small mistake in my earlier message : I meant the folder /examples/laminar/cylinder3d/

[sthavishtha]

Dear iJokerify

You must place the cylinder3d.stl file (available in the /examples/laminar/cylinder2d/ folder) in the folder where you run your code.

Regards
Sthavishtha

[sthavishtha]

Dear iJokerify

Are you sure that gnuplot is installed? You can verify its location using which gnuplot in your terminal.

Regards
Sthavishtha

[sthavishtha]

Dear Dr. Mathias

Thanks for your comments and sorry for the delayed reply. I tried both BGK and MRT, along with other boundary conditions – LocalBC, InterpBC and Zou-HeBC. All of them yield similar converged streamline/velocity profiles. So, I believe that this is how the physical solution should be.

Regards
Sthavishtha

[sthavishtha]

Dear Mathias

Thanks for the suggestion. Here is the updated plot for the same Re and different grid sizes. The streamline profiles from 64 x 64 don’t exactly match with that at higher grid sizes due to grid dependence. However, the profiles at higher grid sizes (512 x 512) are still off from the literature.

I do agree that one cannot expect a steady state solution for higher Re. But Re = 1000 also is not very high enough to expect an unsteady solution state.

I am now planning to try this by adopting MRTdynamics2, as you state in the code that this uses relaxation times for higher stability. So, is replacing MRTdynamics with MRTdynamics2 in the code and using the same descriptor MRTD2Q9Descriptor the right approach to invoke this?

Regards
Sthavishtha

[sthavishtha]

Dear Dr. Mathias

Thanks for your fast reply.

I was actually referring to the peak in the residual convergence plot at around 100,000 time steps (plot of residual error vs number of time steps) at the link. I compute the residual error as energy1 - energy0)/energy1 where energy1 and energy0 are sLattice.getStatistics().getAverageEnergy() computed at the current time step and previous time step respectively.

Though sudden peaks and troughs are possible in such residual convergence plots, the reason I call this as a “Spurious peak” is because I notice a typical change in the flow structure at a time instant around this peak only at high Reynolds numbers. This was not noticed at low Reynolds numbers.

Regards
Sthavishtha

[sthavishtha]

Dear Behnamandi

The partial slip boundary condition is already available via the function void addPartialSlipBoundary(...), listed in boundaryCondition2D.h/boundaryCondition2D.hh. An example of its usage is also available in examples/laminar/poiseuille2d/ and examples/laminar/poiseuille3d/ – you will have to use boundaryType == partialSlip in those code examples.

Regards
Sthavishtha

[sthavishtha]

Dear Adrian

Perfect, that works. The question I have is : which member function is invoked when calling velocityPlane(vel, latticeR)? I ask so because, I don’t find any member function in blockReduction2D2D.h/blockReduction2D2D.hh which is of the format BlockReduction2D2D(T[], int[])?

Additionally, for the case of 3D, wouldn’t it be just replacing BlockReduction2D2D with BlockReduction3D2D and proceeding as per your snippet itself?

Thanks

Regards
Sthavishtha

[sthavishtha]

Dear Marc

Noted. Thanks for the information.

Regards
Sthavishtha

[sthavishtha]

Dear Adrian

Thanks for the reply. Unfortunately, this doesn’t work as get() is not a member of the class BlockReduction2D2D (see the error below).

cavity2d.cpp:224:30: error: ‘class olb::BlockReduction2D2D<double>’ has no member named ‘get’
             << velocityPlane.get(iX, iY, 0) << " "
                              ^
cavity2d.cpp:225:30: error: ‘class olb::BlockReduction2D2D<double>’ has no member named ‘get’
             << velocityPlane.get(iX, iY, 1) << endl;   

^

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