[vinerm]

Slip velocity exists only for Euler-Euler model or for mixture model with Slip enabled. The way to determine slip velocity depends on the model being used.

[hassanayaz]

i am using eulerian model for slip velocity

[vinerm]

Then it is simple. Just take a difference of velocities of two phases.

[hassanayaz]

Hello
I am working with corrugated wall geometry in ansys fluent... i want to make periodic boundary conditions but while doing it i face an issue that "computed translation deltas: -0.018897 0.000000 -0.367696" something like that in console. kindly guide what type of error is it? and how to resolve it?

[vinerm]

That's not an error, but information about the difference between the normals of two periodic boundaries.

[hassanayaz]

below this line the following shown
Error: Failed to make zones periodic.
Error Object: #f
so what can i do to resolve it???

[vinerm]

This implies that the boundaries you want to make periodic are either not aligned with each other or they do not have conformal mesh. If the boundaries do not have conformal mesh, then you can either go back to Meshing tool, whichever you used, and ensure that both boundaries have same mesh within a certain tolerance or you can make use of Mesh Interface in Fluent. Convert both boundary types to Interface and then use Mesh Interface to define an interface of type Periodic Boundary.

[hassanayaz]

how to convert boundary type to interface????
i am doing meshing with patch conforming method is there any issue with this type of meshing for converting boundary type to interface type?????

[vinerm]

Mesh Interfaces in Fluent are compatible with almost all types of meshes. Patch conforming generates tetrahedral mesh and you can use it to generate interface. However, recommended method would be to use Face Matching in Meshing to generate same mesh on the boundaries that are supposed to be periodic. Then, you will not have to use interfaces.

[hassanayaz]

Originally Posted by vinerm

Mesh Interfaces in Fluent are compatible with almost all types of meshes. Patch conforming generates tetrahedral mesh and you can use it to generate interface. However, recommended method would be to use Face Matching in Meshing to generate same mesh on the boundaries that are supposed to be periodic. Then, you will not have to use interfaces.

thanks a lot!
when use face meshing then translation delta problem was there.......
i have create interfaces and while doing periodic zone there was a question that
" create matching interface? [no]"
what is this???
also guide that after periodic zones created there is something like "inlet_outlet-side1-wall-inlet" similar for other boundaries... what are these?? can they effect simulation results???

[vinerm]

That's just a confirmation and need to be answered as Yes. It will also ask whether you want rotational or translational periodic. Periodic boundary will be created only if the mesh on both boundaries is same within a certain tolerance. Else, use Mesh Interface.

[hassanayaz]

Originally Posted by vinerm

That's just a confirmation and need to be answered as Yes. It will also ask whether you want rotational or translational periodic. Periodic boundary will be created only if the mesh on both boundaries is same within a certain tolerance. Else, use Mesh Interface.

i am using translational periodic... mesh is not same so i use interface method and then there was additional things like" inlet-outlet-side1-wall-inlet" similar for other boundaries.... will they effect the simulation results??

[vinerm]

Those are created because the mesh is not 1-to-1 match. So, any extra area is converted into walls. If the overlap is more than 95%, it should not cause any trouble.

[hassanayaz]

Originally Posted by vinerm

Those are created because the mesh is not 1-to-1 match. So, any extra area is converted into walls. If the overlap is more than 95%, it should not cause any trouble.

is there any method to find how much they overlaped??

[vinerm]

That would not be easy. You need to display both on top of each other for visual comparison. Otherwise, it would require rather sophisticated programming wherein you need to loop over only the outermost faces of the boundary and then compare the angles of the edges as well as positions of the nodes. Don't worry too much about it.

[hassanayaz]

thanks a lot
i applied non conformal periodic conditions and work with fluidization after simulation solid volume fraction is shown zero and gas vol fraction shown 1 everywhere... what will be the problem???

[vinerm]

Are you using periodic condition with fluidization? How is fluidization periodic in translational direction?

[hassanayaz]

Originally Posted by vinerm

Are you using periodic condition with fluidization? How is fluidization periodic in translational direction?

i am not exactly sure that either use translational or rotational.... guide if something helpful for me

[vinerm]

Periodic conditions are used if the system is periodic geometrically as well as physically, e.g., a fan or an impeller can almost always be modeled using rotational periodic conditions since depending upon the number of blades, the rotor geometry repeats itself every angular coordinate. However, if the stator is to be involved in the model and the stator is not periodic, then it rotational periodicity cannot be used. Similarly, flow through a straight channel of any shape as long as the cross-section profile repeats itself every X units of length throughout the length can be modeled using translational periodic condition. It is not just the geometry, but the physics must also be periodic. Otherwise, periodicity cannot be invoked.

[hassanayaz]

Hello
i need guidance about solution convergence in fluent...... which values required is to change for solution convergence.... kindly guide...
i did the following
change the method for solution
change relaxation factors
change #of iterations per time step....

some times solution converged for some initial time step and then no convergence.... also guide about it