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-   -   Is this simmulation possible on an i7? #cells/cell size? (https://www.cfd-online.com/Forums/openfoam-solving/113161-simmulation-possible-i7-cells-cell-size.html)

 klausb February 13, 2013 17:22

Is this simmulation possible on an i7? #cells/cell size?

Hello,

I need to do some simulations of a hydrofoil. The objective is to minimize drag and optimize lift/drag. The hydrofoil operates in water, at speeds up to 15m/s, has a reference length/chrod of 0.1m and a wing span of 1m.

The turbulence model is kklomega. The case is 3D / symmetric hence the simulated wing span will be 0.5m.

y+ = 1 >> wall spacing (with roh = 1000kg/m3 and dynamic viscosity = 0.001002 kg/ms) = 0.000001617678382235965m (calculated with http://www.pointwise.com/yplus/)

Assuming 15 layers will be enough to resolve the boundary layer? this looks like a huge case - too huge for an i7 with 8Gb Ram?

What would be a good choice for the cell size in the boundary layer region (x and z dimension assuming y is the wall spacing mentioned above)?

Any other ideas about how to approach this case?

Klaus

 immortality February 13, 2013 22:32

hi
How do you want to optimize airfoil?active or passive?

 sushant February 14, 2013 06:24

A mesh of 5,000,000 cells works fine for me on i7 with 8GB (4x parallel). Sure, you're not going to solve it in an hour, but I would leave it overnight and have it ready the next morning.

You can stretch it to 7,000,000 probably, but it gets uncomfortable beyond that, memory being the constraint.

 klausb February 14, 2013 14:35

I assume active means using a routine that varies some parameters of the shape based on given rules and simulation results? And passive means doing a row of simulations based in different "fixed" configurations.

According to these definitions, it's the passive approach following a thesis related to the optimization of a Boeing plane wing by means of retrofitted winglets.

 klausb February 14, 2013 14:56

I can easily upgrade to 16Gb or even 32Gb RAM if that's the constraint.

But I am struggling to estimate the required cell size (apart from the wall spacing) and number of layers required to resolve the boundary layer to be able to estimate the case size (number of cells) required to figure out whether the available hardware is sufficient or whether I have to invite some friends to a lan party.

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