[ANSYS Meshing] Last Aspect Ratio Prism Layer Ignoring requrested layer numbers

u2berggeist · October 3, 2016, 09:39

Hello all,

I am currently doing an external flow analysis of a racecar (Formula SAE is you're familiar with that). The car has wings and other aero attached, so I am trying to analyze their performance.

To that end, I am wanting to resolve the boundary layer fully on those parts (and the tires as its wake has a great affect on total car performance aerodynamically) and resolve the boundary layer using wall function for everything else (ie. the bluff body mock up of the body and driver). In addition (and the main point of this post), I am also wanting to place more prism layers in these areas.

I am using last aspect ratio as the inflation method (first layer height is failing for one reason or another). When I try and increase the layer count, ANSYS mesh does nothing different for some reason (ie. I originally had everything at 10 layers. I changed the Aero elements to be 20 layers total, and upon visual inspection there appear to be only 10 layers, so no increase in layer count).

I will be running the simulation in CFX using K-omega SST and am using local inflation functions to define the inflation settings.

So, is there something I'm missing? Does Last Aspect Ratio cap the number of layers that can be used? I realize that I'm technically defining the maximum number of layers that can be used, but I've never had the number specified not be reflected in the mesh.

u2berggeist · October 3, 2016, 15:31

Update: It also doesn't let me specify layers over 10 with First Layer thickness either.

October 3, 2016, 09:39	Last Aspect Ratio Prism Layer Ignoring requested layer numbers	#1
u2berggeist Member James Wright Join Date: Oct 2015 Posts: 40 Rep Power: 10	Hello all, I am currently doing an external flow analysis of a racecar (Formula SAE is you're familiar with that). The car has wings and other aero attached, so I am trying to analyze their performance. To that end, I am wanting to resolve the boundary layer fully on those parts (and the tires as its wake has a great affect on total car performance aerodynamically) and resolve the boundary layer using wall function for everything else (ie. the bluff body mock up of the body and driver). In addition (and the main point of this post), I am also wanting to place more prism layers in these areas. I am using last aspect ratio as the inflation method (first layer height is failing for one reason or another). When I try and increase the layer count, ANSYS mesh does nothing different for some reason (ie. I originally had everything at 10 layers. I changed the Aero elements to be 20 layers total, and upon visual inspection there appear to be only 10 layers, so no increase in layer count). I will be running the simulation in CFX using K-omega SST and am using local inflation functions to define the inflation settings. So, is there something I'm missing? Does Last Aspect Ratio cap the number of layers that can be used? I realize that I'm technically defining the maximum number of layers that can be used, but I've never had the number specified not be reflected in the mesh. Last edited by u2berggeist; October 3, 2016 at 11:58.

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October 3, 2016, 15:31		#2
u2berggeist Member James Wright Join Date: Oct 2015 Posts: 40 Rep Power: 10	Update: It also doesn't let me specify layers over 10 with First Layer thickness either.