[pdp.aero]

Originally Posted by Rajan

Hi Everyone,
I am very new to Pointwise and CFD in general and need to generate a three dimensional structured Volume mesh for cyclone separator as part of a university project.
I have imported the geometry from cad software and attempted a surface mesh by selecting domains on database entities.Now i want to generate volume mesh all over the region.
Any help or advice on how to approach this problem would be greatly appreciated
here i am posting the screen shot of the model.

Hi ,

From what I had seen in your geometry picture, I am suggesting you three ways. I personally go for the third way, it will be more convenience.

1-For not losing orthogonality at the tangent portion of the channel's entry, you need to create unstructured block in the channel and create structured block in your body. For linking these blocks, you need to define grid interface. Because you are connecting unstructured block to structured block the grid interface will be non-conformal.

1-1 Create your structured block in the body which includes the structured tangent boundary at the entry from the channel (you can use revolve for creation or follow my way for structured block creation explained in the second way).

1-2 Split your tangent interconnection boundary from your structured body block

1-3 Go to the Create>Diagonalize>Initialize and select the split boundary. In this way you will have an unstructured surface mesh which matches exactly to you structured surface mesh at the entry.

1-4 Create your unstructured block in the channel which includes the unstructured tangent boundary at the entry to the body.

1-5 Set the boundary condition for the structured and unstructured tangent surface mesh to the interface.

1-6 Set two separate zone for your unstructured channel block and structured body block in the CAE>volume condition.

1-7 Go to the Fluent. From Define>Grid Interface. Create an interface between two zones. For this purpose, just select the tangent structured surface mesh at the entry from structured zone and tangent unstructured surface mesh at the entry from unstructured zone and type a name for it.

Note: Using grid interface means that you are creating hanging node and your cell value will be interpolated between zones.

2- I assumed that you are not supposed to define boundary condition at the interconnection between the channel and body. If it is true you may follow this way, otherwise you need to use the first way.

2-1 Divide the body into 3 parts. One part at the top, one at the bottom and the last one exactly fit to the interconnection's entry. After you divide your surface mesh, you will have four horizontal sections. One locates at the top, next at the top of the interconnection's entry, one at the bottom of the interconnection's entry, and the last one at the bottom of the body.

2-2 You will create your structured surface mesh at each horizontal section. First, you need to mesh the sections at the top and the bottom of the interconnection. For this please refer to the picture 1.

2-3 You will create your surface mesh for the section at the top of the body.

2-4 You will create your surface mesh for the section at the bottom of the body.

2-5 Define interface grid surface. Because the topology of the surface mesh at the top and bottom of the interconnection differ from the topology of the body you need to define non-conformal structured grid interface between mesh surfaces at the bottom. For this purpose, just mesh a circle that fits at the bottom section of the interconnection. Then, set the boundary condition of the surface mesh that covers each other to interface. Define a separate zone for the interconnection portion and bottom of your body in CAE>Volume condition. Go to the Fluent and then "Define>Grid Interface". Create an interface between domains that covers each other.

Note: For creating your structured mesh as described in picture 1, you need to use grid>solve, select Steger-Sorenson boundary control function and select float for inner connection, then iterate for 30 steps as an example.
For creating your structured mesh at the top and bottom sections as described in “1stway”, you need to define a diameter connector, split two edge connectors at the 25 and 75 percent of the length. Distribute your nodes on the edge, create your domain and run the solver.

3-For escaping from using non-conformal grid interface, there is another way. From this point, in the first way you need to create unstructured channel block by selecting the structured tangent surface and assemble your domain. In this way Pointwise will define a pyramid cells between the structured and unstructured block.

All the Bests,
Payam