Learning Forum

[Prashant Jha]

Hello all, I want to analyse 3D rectangular wavy microchannel heat sink for studying heat transfer characteristics but don't know how to model the wavy profile in ansys design modeller. Please someone help me out with this.

Thanks

[Luca B.]

First of all, why do you prefer to use DesignModeler? Ansys provides now new softwares like Ansys Discovery or Ansys SpaceClaim who can provide you best tools to create your geometry.

Can you share a picture of the final application you want to recrate. My suggestion is to use a sketch approach with splines to create your profiles. If manually you cannot create it, there is also the chanche to use script to generate your model.

 

Luca

[Rob]

Just a note on scale. Do NOT build the channel in real scale: CAD kernel tolerances tend to merge micron scale parts into a corrupted mess. Scale up and then rescale in Fluent when you import the mesh. A 2mm channel should be fine, 20microns will almost certainly not be. 

[Prashant Jha]

@Luca, I am new to ANSYS, and have used design modeler only for my college projects, so is unaware of the functionalities and features of other geometry creation tools. Ok, as per your advice, I will try them. Please find the schematic alongwith the dimensions. The hatched portions are the wavy channels with profile given by cos function as defined in the another image. So, how to create these cosine function profile on a micrometer scale. Just one more query, that can we make parametric designs in spaceclaim??

@Robb, I couldn't understand your point. Could you please elaborate by taking example of any dimension provided here. 

Thank You

[Rob]

OK, the channel is around 200 microns across. CAD kernels (the backend geometry tool that the interface sits on) tend to be accurate to a fraction of a mm but aren't designed to work with micron scale domains. However, most are good with mm or higher. So, if you make your channel 2 or 20mm across you should avoid issues with the kernal tolerance functions. Then mesh WITHOUT scaling. 

In Fluent we can scale the mesh very accurately back to the correct dimensions. 

As an aside, if you're trained on one of the CAD tools just use that and export Step or another supported format for use in the Ansys geometry tools. The supported list is in the same place you downloaded Student. 

[Prashant Jha]

ok thanks. i got it. Just one more query, if I model the geometry in some other software as parametric design, then will the parameters be retained while importing the geometry in ansys??

[Rob]

It depends. If you have the CAD readers (ie the right licences) then yes. Otherwise, no. With Student, and I think Academic, licence you won't have the readers. 

[Prashant Jha]

Hi, I tried a lot in different ways, but I am not getting how to get cosine curve as per the requirements, could you please help me out?? It would be of immense help to me.

[Rob]

In DM I'd work out the positions of the points and use the construction points. Then sketch with one of the line options (polynomial?).