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EMC2 · 04-05-2002, 08:19 PM

Roscal - your English is fine

CFD is even better

Which CFD program are you using?

Brad and Fixiit - those are pics of the water velocity. The top one is a good example of the type issue I was talking to DoTheDog about.

The scale shows what color represents what velocity (speed) the water at a particular point has. Darkest blue is 0 (no flow), red is equal or greater than the highest flow he has scaled.

You can see the effects turns have on the flow (usually highest on the "inside" of the turn, slowest on the outside).

You can also see fairly clearly the turbulence in the middle picture near the walls, as well as the boundary layer (0 or near 0 velocity) right up against the walls in a lot of areas.

Fixiit - the only temperature you assign when doing the thermal side of the simulation is the inlet water temperature and the boundary temperatures (you specify say 1/2" from the block surface the ambient temperature is 30C). The other inputs are usually the inlet/outlet pressures or the input flow rate and the heat flux and area it is applied to (the size of the CPU die and the amount of power you are wanting to model).

The CFD software then calculates everything else (if it's good software). It starts with the water velocity, which determines the heat transfer coefficient (how well the heat is conducted to and through the water). It then uses these values, the thermal resistance of the block itself, and the input power to calculate all the temps.

04-05-2002, 08:19 PM	#5
EMC2 Cooling Savant Join Date: Feb 2002 Location: Dark Side of the Moon Posts: 365	* I know nothing * :P Roscal - your English is fine CFD is even better Which CFD program are you using? Brad and Fixiit - those are pics of the water velocity. The top one is a good example of the type issue I was talking to DoTheDog about. The scale shows what color represents what velocity (speed) the water at a particular point has. Darkest blue is 0 (no flow), red is equal or greater than the highest flow he has scaled. You can see the effects turns have on the flow (usually highest on the "inside" of the turn, slowest on the outside). You can also see fairly clearly the turbulence in the middle picture near the walls, as well as the boundary layer (0 or near 0 velocity) right up against the walls in a lot of areas. Fixiit - the only temperature you assign when doing the thermal side of the simulation is the inlet water temperature and the boundary temperatures (you specify say 1/2" from the block surface the ambient temperature is 30C). The other inputs are usually the inlet/outlet pressures or the input flow rate and the heat flux and area it is applied to (the size of the CPU die and the amount of power you are wanting to model). The CFD software then calculates everything else (if it's good software). It starts with the water velocity, which determines the heat transfer coefficient (how well the heat is conducted to and through the water). It then uses these values, the thermal resistance of the block itself, and the input power to calculate all the temps.