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-   -   Directed Mesh (http://www.cfd-online.com/Forums/star-ccm/113871-directed-mesh.html)

badger1 February 28, 2013 08:50

Directed Mesh
 
Hi
I have an aerofoil as shown on the image and I am using a polyhedral mesh.

I wish to create a structured mesh in the region on the wake shown by the box.

I have created a mseh using the directed mesh function. and have meshed the box with the structured mesh.

How do I then mesh the rest of the geometry without creating two meshes that overlap?

thanks

grad@itu February 28, 2013 08:54

There is no picture, and because of this i have no idea.. if you can put, wen can say something.

And why do you use directed mesh option?

badger1 February 28, 2013 08:56

1 Attachment(s)
Sorry the picture should be attached to this.

I dont really know how else to do it so I thought that a directed mesh would be the best way I am fairly new to starccm+

grad@itu February 28, 2013 09:07

ok. now,

first why do you use a rectangular region? is there any specific reason? if there is no specific situation. You can use rectangular domain.

second, whatever you mesh this domain the overlap does not occur.

third, there is two method to form finer mesh on the wake area.

1. Use trimmed mesh, there is an specific option "trimmer wake refinement". its advance here, if you change mesh size in domain, wake refinement region remeshed automatically. And you only enter wake refinement lenght..

2. Use any mesh, but absolutelu poly mesh and then you can use "volume shape" option. You can use rectangle, conical, spherical or cylindirical shapes in the region whereever you want (rectangle place in your picture). You must specify a mesh size(absolute or relative) and this are will have finer mesh..

Thats all..

badger1 February 28, 2013 09:11

I am wanting to create a polyhedral mesh on everything except the area indicated by the rectangle.

I tried a volumetric shape but it just refines the mesh further with a polyhedral mesh not a structured mesh.

How would I go about creating the different meshes? is the wake refinement only avaliable if the whole mesh is trimmer?

thanks

grad@itu February 28, 2013 10:02

if you create different meshes on different areas, then you have to create two different regions.

For your study, you create two mesh continuumi Mesh 1 is Poly, Mesh 2 is Trimmer or other..

But you have to create two discrete region, you have to divide geometrically your refinement area. Later you have to some boundary combine/interface operations to form conformal mesh.

Note : Trimmer mesh cant use multi region applications - for conformal mesh - you can use complete trimmer or polyhedral mesh with appropriate prism layer mesh..

badger1 March 1, 2013 11:11

thanks that is very helpful. Do you think there is an easier way to do this?

I esencially just want a structured mesh in the wake region and it to blend nicely with the prism layers and the polyhedral mesh around it.

grad@itu March 1, 2013 14:29

I have to try may be but be sure trimmer meshing model useless in multiregion problems(iif you desire conformal mesh)..

And i dont know more easier way to do it. You can try the seperate the regions and use interfaces between two regions and just try..

Or you will use trimmer mesh everywhere on the region and you will use volume shape. And dont forget if you can use prism layers you see the enough quality meshes near the wall..

And you should try different meshes and differen mesh densities.. May be you dont need the structured mesh in the wake region. You must compare the solutions.. are you sure? you need the structured mesh? or poly mesh outside the wake region? why?


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