Hi, Thanks for the reply. I think I should be able to do that. Thanks again! Swagat On Fri, May 31, 2019, 7:03 PM Stanisław Gepner <sgepner@meil.pw.edu.pl> wrote:

Hi Swagat,

The MovingReferenceFrame has been implemented only for constant velocity of the Frame. That is it can not be a function of time and space. So I am afraid it will not work the way you are trying to do it here, only by putting appropriate values in the xml file.

What I meant is, that if you know what terms you need to add to the NS equation, you could manipulate the source of Nektar - essentially write a new Forcing function - very mych like the MovingReferenceFrame is written. There the NS equation is supplemented by sth. like

c_x * \partial u / \partial x

with c_x the speed of the moving frame.

Cheers, Stan

On pią, 2019-05-31 at 18:20 +0900, Swagat Kumar Nayak wrote:

...

Hi Stanisław,

Thanks for your reply. I checked the files. I think that if I add the frame velocity and the appropriate Initial and Boundary conditions, then I hope that it should work for me. Though, I am unsure about its implementation. Does the way I am implementing it, seem correct?

<NEKTAR> <!-- Setting the Expansion Bases --> <EXPANSIONS> ............................. </EXPANSIONS>

<!-- Setting the Filters to output Energy Details --> <FILTERS> ............................. </FILTERS>

<!-- Setting the Boundary conditions and Solver information for the flow --> <CONDITIONS> <SOLVERINFO> .............................. </SOLVERINFO>

<PARAMETERS> ............................. </PARAMETERS>

<!-- Setting the Variables -->

<VARIABLES> <V ID="0"> u </V> <V ID="1"> v </V> <V ID="2"> w </V> <V ID="3"> p </V> </VARIABLES>

<!-- Setting the Boundary Conditions --> <BOUNDARYREGIONS> ........................................ </BOUNDARYREGIONS>

<BOUNDARYCONDITIONS> ................................................. </BOUNDARYCONDITIONS>

<!-- Setting the Initial conditions and the frame velocity (Precession frame) -->

<FUNCTION NAME="InitialConditions"> <E VAR="u" VALUE="F(y)" /> <E VAR="v" VALUE="G(x)" /> <E VAR="w" VALUE="0" /> <E VAR="p" VALUE="0" /> </FUNCTION>

<FORCE TYPE="MovingReferenceFrame"> <FRAMEVELOCITY> <FUNCTION NAME="MovingReferenceFrame"> <E VAR="u" VALUE="f(y,z,t)" /> <E VAR="v" VALUE="g(y,z,t)" /> <E VAR="w" VALUE="0" /> </FUNCTION> <FRAMEVELOCITY/> </FORCE>

</CONDITIONS> </NEKTAR>

Thank you ! Swagat Kumar Nayak

On Wed, May 29, 2019 at 7:14 PM Stanisław Gepner < sgepner@meil.pw.edu.pl> wrote:

...

Hi Swagat,

Not sure anyone answered this.

1) You could try to add a Forcing term. Much like ForcingBody in library/Solverutils/Forcing. I think something similar to what you describe has been done for the moving reference frame (ForcingMovingReferenceFrame) i.e. additional terms that are gradient of velocity.

2) At the end of the .geo file there is a protion where Physical objects are declared. Sth. like:

Physical Line(1) = {3,1,2,4}; Physical Surface(2) = {6};

My experience with NekMesh is that composite 2 is the 2D domain and composite 1 the boundary.

Cheers, Stan

On czw, 2019-05-23 at 14:25 +0900, Swagat Kumar Nayak wrote:

...

Hi everyone,

I am trying to simulate the flow of a precessing cylinder in the cylinder frame of reference. I have got some additional terms in the incompressible Navier-stokes equation which are velocity dependent. (1) How do I add these additional terms to the incompressible Navier- stokes equation?

(2) When I create a mesh in Gmsh and try to convert it into the .xml file format, how do I identify the composites corresponding to the global boundaries?

I am new to this framework. So, any help will be largely appreciated.

Thank you,

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