Computational Fluid Dynamics for design - Page 2

EMC2 · 04-06-2002, 11:58 AM

Fixitt - Roscal has said yes - if you can't create what he needs, my offer to help stands.

On the top issue - notice my conditionals (wall height, thickness, and thermal bond - also influenced by thermal conductivity of the block).

JD - two ways around your problem, one would require a little ingenuity.

Take the block itself and rotate it in relationship to the end mill's axis in your vice to create the angle (the ingenuity part). Just rotate the pic I made so the end mill is vertical to see what I mean

You could also add some bottom channel features by using the endmill sort of like a drill - making small circular depressions in the bottom, overlapped at different heights, and irregularly spaced.

TiTch · 04-06-2002, 12:07 PM

I was not thinking of the ones like the maze but the acrylic ones like at www.cooling-solutions.de or on this thread

http://forums.bit-tech.net/showthrea...&threadid=6909

However, thinking of what you are saying, it would make no difference.

jaydee · 04-06-2002, 12:13 PM

Quote:

Originally posted by EMC2
Fixitt - Roscal has said yes - if you can't create what he needs, my offer to help stands.

On the top issue - notice my conditionals (wall height, thickness, and thermal bond - also influenced by thermal conductivity of the block).

JD - two ways around your problem, one would require a little ingenuity.

Take the block itself and rotate it in relationship to the end mill's axis in your vice to you create the angle (the ingenuity part). Just rotate the pic I made so the end mill is vertical to see what I mean

I already though about that and tried it but my endmills are not long enough. I only have about a inch. If I put the block itself in there at an angle then the endmill holder hits the block before the endmill can get much done. Also the spindal colum on my mill rotates!!! but it still has the same problem with endmill length. That can be solved by using longer endmills but I am not going to buy new ones any time soon. I also want to get a vise that has the axis on it already so i don't have to take the block out of the vise untill it is done. But that is another $100.00+ I don't want to spend right now.

I am in the note taking stage right now. Next winter I will have the reasources and the TIME to do some of this stuff. I will try to work on Brads block when I can though, but I need that holder which is $30 and I am going to wait to see if Fixittt can get some machined through his contacts before I buy one from Sherline.

This is the last weekend i will have to do much, and my mill is down.

Next weekend I have my daughter and Monday i am headed to CA on a road trip job for work. Then it will be road trip after road trip untill next winter.

jaydee · 04-06-2002, 12:15 PM

Quote:

Originally posted by EMC2

You could also add some bottom channel features by using the endmill sort of like a drill - making small circular depressions in the bottom, overlapped at different heights, and irregularly spaced.

This is good but 1/8" is as small an endmill I can use. I will give it s shot when I can.

EMC2 · 04-06-2002, 12:31 PM

Ooops - my bad JD - when I said small I should have instead used the word shallow

ps. The 1/8 will do fine.

Brad · 04-06-2002, 03:21 PM

notice how the inside wall of almost all channels has very little flow, this is obviously where a spiral is better.

The idea of running the block at an angle to cut cresents in it is really good, I'd like to see this done. Also, that picture shows a grey cylinder cutting into the block, what about having the inlet barb on an angle?

Marco · 04-07-2002, 07:39 AM

Quote:

Originally posted by Brad
notice how the inside wall of almost all channels has very little flow, this is obviously where a spiral is better.

I'm just going to go with intuitive logic here, but you'd expect that with centrifugal force you will be getting faster movement around the outside rather than the inside.

You can run a sim like that for -any- .IGES design? Shit I need to bust out solidworks. That analysis is done in 3d right? So what happens, you produce cross-sections at different depths? What software is it that you use again? And does it take alot of training to use it? Or is it fairly intuitive? Because I might be able to gain access to it...

Furthermore, can you do something more than just the fluid flow patterns? can you factor in thermal characterstics as well? Or even just do thermal characteristics ignoring fluid flow?

TiTch · 04-07-2002, 08:03 AM

www.digital-explosion.co.uk created a block that works on a whorle pool effect with pins over the cpu for increased surface area and turbulance. This would surely be a more efficient model as the only linear flow will be well away from the cpu.

Roscal · 04-07-2002, 08:14 AM

MArco >The analysis is done in 3D. I prefer IGES format but I can take various formats from different CAD software.
When all the nodes are computed I can view where I want in any positions, the soft used is Cosmos Flow for the moment. I do other studies in order to use another soft called Fluent (the best in the world).
To use thes softwares knowledge of fluid mecanics is required, but Cosmos is easy to use (relative) but not Fluent

Thermal characterstics and others properties like radiation, etc can be used but it become very heavy and complicated. I realize some simple attempt to view how it works...
I do, in this moment, a simulation more precise for the maze2. have +7 hours of calculations and +300Mo in RAM so coupling Température should be very hard to do

(Only Duron 700@1000)

For further informations take a look at : http://www.cosmosm.com

++

EMC2 · 04-07-2002, 03:46 PM

Ah yes, the "expense" (in computer time) of accurate CFD.

While you're looking at purely the flow side of things, you might find it interesting to do a little bit of look see at the affects of a channel's aspect ratio (height versus width) with respect to flow (but you need to use pressure for the boundary conditions on the channel, not volumetric flow rate).

To save yourself computer time, you can model a sub-portion of a block with a single rectangular channel that has only 1 bend in it's path (U-shaped section) and constant dimensions along it's length.

Roscal · 04-07-2002, 04:43 PM

EMC2> I have finished the new simulation more precise than the others but with more computer time

.

Pic about speed into a maze2 (red is high flow, blue is low flow)

We can see well the "unsticking" (in blue) at each corner of the maze due to a high speed of the water flow. And as you say EMC2 I have modeled a sub-portion as the pic below to view if breaking the corner of my waterblock can improve speed at the wall near the corner and "down" the boundary layer.

With this sub-portion I can put a big number of nodes (meshing) in order to have a good description of the phenomenom to view if a chamfer is necessary or not.

++

Fixittt · 04-07-2002, 06:25 PM

I got nothing but red X`s

ECUPirate · 04-07-2002, 07:54 PM

None of Roscal's pics are showing up... just red x's. (even the first pics.) ....even with netscape.

Volenti · 04-07-2002, 09:42 PM

Here's a thought, (looking at the last hi resolution maze2 pic) what if you re-design the channels, keeping everything pretty much the same, but make the blue areas (especially the parts after the sharp corners) solid metal, thicken the walls there so to speak, and see what the flow does then?

jaydee · 04-07-2002, 10:16 PM

I thought this was the maze 2?

Where are those images coming from?

Slipstream · 04-08-2002, 02:07 AM

If you guys are so worried about fluid velocity in your channels how come you use such large channels?

I personally made my WB by using the smallest milling bit the operator would let me. And I do not believe parallel channels are effective because surface area in a waterblock is not as critical as fluid velocity. (I did a quick heat transfer calc)

I believe the increased velocity by using a series maze style waterblock with many small channels in series overcomes the loss in flow rate due to the pressure drop over the waterblock.

I think velocity in the WB is important not flow rate.

To achieve this end I would suggest smaller fluid channels in series rather than different configurations.

Brad · 04-08-2002, 03:34 AM

jaydee, I was wondering that too

\

slipstream, thats all fine but you need to remember that mag drive pumps don't have much psi, so the water flow will slow right down

TiTch · 04-08-2002, 03:59 AM

Isn't that the result that overclockers.com got with the gemini block with its small chanells, who out performed the larger chanelled maze 2 and single chamber swiftech.

EMC2 · 04-08-2002, 07:16 PM

JD - I just thought he was labelling his different test blocks consecutively, lol :shrug:

Slipstream - actually the main discussion here was affects of channel geometry to velocity and using CFD software

(at least that's been my take on it)

Brad - regarding the angled input... that would help lower the inlet restriction and decrease the side of the low flow area at the inlet, but an easier way to address the problem of the low flow in the back 1/3 of the inlet area might be to simply offset the inlet from the die's location so that area is outside where you are wanting maximum heat transfer rates (which is over the die). In the case of a spiral, that kind of fubars things though, so an alternative would be altering the inlet area's geometry to address the problem.

ondaedg · 04-08-2002, 11:42 PM

slipstream brings up a good point. Perhaps someone here can produce two blocks that we can test this out. The blocks would have to be of equal surface area. This would obviously be a constant.

The first block would be a high flow block with parallel channels. This could be done by using a design such as Xjinn's or a maze style block with multiple channels running parallel.

The second block would be a maze design that is one long maze using narrow channels.

The pump to do this should obviously be a fairly high powered pump. I have a 500 gph 7.5 psi pump that would be plenty strong so that it would not be a bottleneck when testing these. To put that into perspective, it can pump water straight up for almost 20 feet.

The high velocity of the narrow channeled block may indeed address the subject of this thread which is laminar flow and turbulence. I think it's worth a try and I would be more than happy to help make this work.

Brad · 04-09-2002, 02:09 AM

emc2, offset the centre, have a turbulant design directly over the core.

sounds good?

Dix Dogfight · 04-09-2002, 08:55 AM

Nice to see some calculations/simulationss on this interesting matter.
One observation i've made is: All new blocks (maze,spiral.....) have a center inlet above the CPU core.
These simulations show that the turbulence on one side of the inlet is wery small. Wouldn't it be better if the inlet is slightly offcenter to have maximum turbulence over the core?
Just my 2 cents.

Pinkster · 07-22-2002, 07:12 AM

still dont see any of roscals pics damn...
still a very informative thread

Roscal · 07-22-2002, 07:25 AM

Quote:

Originally posted by Pinkster
still dont see any of roscals pics damn...
still a very informative thread

If you want pics or anims go here (website was changed):

http://membres.lycos.fr/roscool/fotos/Simulation_num/

http://membres.lycos.fr/roscool/

I don't have time to continue studies and comparisons for the moment..

04-06-2002, 11:58 AM	#26
EMC2 Cooling Savant Join Date: Feb 2002 Location: Dark Side of the Moon Posts: 365	Fixitt - Roscal has said yes - if you can't create what he needs, my offer to help stands. On the top issue - notice my conditionals (wall height, thickness, and thermal bond - also influenced by thermal conductivity of the block). JD - two ways around your problem, one would require a little ingenuity. Take the block itself and rotate it in relationship to the end mill's axis in your vice to create the angle (the ingenuity part). Just rotate the pic I made so the end mill is vertical to see what I mean You could also add some bottom channel features by using the endmill sort of like a drill - making small circular depressions in the bottom, overlapped at different heights, and irregularly spaced. Last edited by EMC2; 04-06-2002 at 12:03 PM.

04-06-2002, 12:31 PM	#30
EMC2 Cooling Savant Join Date: Feb 2002 Location: Dark Side of the Moon Posts: 365	Ooops - my bad JD - when I said small I should have instead used the word shallow ps. The 1/8 will do fine. Last edited by EMC2; 04-06-2002 at 12:36 PM.

04-06-2002, 03:21 PM	#31
Brad Thermophile Join Date: Oct 2001 Location: Nuu Zeeelin Posts: 3,175	notice how the inside wall of almost all channels has very little flow, this is obviously where a spiral is better. The idea of running the block at an angle to cut cresents in it is really good, I'd like to see this done. Also, that picture shows a grey cylinder cutting into the block, what about having the inlet barb on an angle? __________________ 2x P3 1100's at 1400, Abit VP6, 2x Corsair 256mb PC150 sticks, 20gb 'cuda ATA-III, 2x 40gb 'cuda ATA-IV in raid 0. 20" Trinitron. No fans 2x 2400+ at 2288mhz (16.0 x 143), Iwill MPX2, 2x Kingmax PC-3200 256mb sticks, 4x 20gb 60gxp in Raid 5 on a Promise SX6000. Asus Ti4200 320/630. Cooled by Water

04-07-2002, 08:03 AM	#33
TiTch Cooling Neophyte Join Date: Mar 2002 Location: London, UK. Posts: 64	www.digital-explosion.co.uk created a block that works on a whorle pool effect with pins over the cpu for increased surface area and turbulance. This would surely be a more efficient model as the only linear flow will be well away from the cpu. __________________ www.gibtek.co.uk

04-07-2002, 06:25 PM	#37
Fixittt CNC Beyatch Join Date: Aug 2001 Location: Tulsa Spell it backwards Posts: 721	I got nothing but red X`s __________________ Creator of the Spir@l Block Longest post ever http://forums.procooling.com/vbb/showthread.php?s=&postid=43808#post43808

04-06-2002, 12:07 PM	#27
TiTch Cooling Neophyte Join Date: Mar 2002 Location: London, UK. Posts: 64	I was not thinking of the ones like the maze but the acrylic ones like at www.cooling-solutions.de or on this thread http://forums.bit-tech.net/showthrea...&threadid=6909 However, thinking of what you are saying, it would make no difference.

04-07-2002, 08:14 AM	#34
Roscal Cooling Savant Join Date: Apr 2002 Location: North of France Posts: 198	MArco >The analysis is done in 3D. I prefer IGES format but I can take various formats from different CAD software. When all the nodes are computed I can view where I want in any positions, the soft used is Cosmos Flow for the moment. I do other studies in order to use another soft called Fluent (the best in the world). To use thes softwares knowledge of fluid mecanics is required, but Cosmos is easy to use (relative) but not Fluent Thermal characterstics and others properties like radiation, etc can be used but it become very heavy and complicated. I realize some simple attempt to view how it works... I do, in this moment, a simulation more precise for the maze2. have +7 hours of calculations and +300Mo in RAM so coupling Température should be very hard to do (Only Duron 700@1000) For further informations take a look at : http://www.cosmosm.com ++

04-07-2002, 03:46 PM	#35
EMC2 Cooling Savant Join Date: Feb 2002 Location: Dark Side of the Moon Posts: 365	Ah yes, the "expense" (in computer time) of accurate CFD. While you're looking at purely the flow side of things, you might find it interesting to do a little bit of look see at the affects of a channel's aspect ratio (height versus width) with respect to flow (but you need to use pressure for the boundary conditions on the channel, not volumetric flow rate). To save yourself computer time, you can model a sub-portion of a block with a single rectangular channel that has only 1 bend in it's path (U-shaped section) and constant dimensions along it's length.

04-07-2002, 04:43 PM	#36
Roscal Cooling Savant Join Date: Apr 2002 Location: North of France Posts: 198	EMC2> I have finished the new simulation more precise than the others but with more computer time . Pic about speed into a maze2 (red is high flow, blue is low flow) We can see well the "unsticking" (in blue) at each corner of the maze due to a high speed of the water flow. And as you say EMC2 I have modeled a sub-portion as the pic below to view if breaking the corner of my waterblock can improve speed at the wall near the corner and "down" the boundary layer. With this sub-portion I can put a big number of nodes (meshing) in order to have a good description of the phenomenom to view if a chamfer is necessary or not. ++

04-07-2002, 07:54 PM	#38
ECUPirate Hottest Stank of them All Join Date: Mar 2002 Location: Washington, DC area Posts: 533	None of Roscal's pics are showing up... just red x's. (even the first pics.) ....even with netscape. __________________ Does a radioactive cat have 18 half lifes? --Kenny my pimpin' rig: ...previously poorly cooled... 486DX-2 66mhz @ 75mhz, 4Mb ram, shared, 256Mb hard drive Onboard VGA, watercooled, of course 16-color monitor, labtec speakers, 28kbs USRobotics modem Windows XP (think about it) Maze 3, DDen GF3 block, Eheim 1250, econoline van HC, 1/2" hose w/ 5/8" fittings Comair 172mm fan

04-07-2002, 09:42 PM	#39
Volenti Cooling Savant Join Date: Jan 2002 Location: in a nice cool spot Posts: 427	Here's a thought, (looking at the last hi resolution maze2 pic) what if you re-design the channels, keeping everything pretty much the same, but make the blue areas (especially the parts after the sharp corners) solid metal, thicken the walls there so to speak, and see what the flow does then?

04-07-2002, 10:16 PM	#40
jaydee Put up or Shut Up Join Date: Dec 2001 Location: Spokane WA Posts: 6,506	I thought this was the maze 2? Where are those images coming from?

04-08-2002, 02:07 AM	#41
Slipstream Cooling Neophyte Join Date: Apr 2002 Posts: 1	If you guys are so worried about fluid velocity in your channels how come you use such large channels? I personally made my WB by using the smallest milling bit the operator would let me. And I do not believe parallel channels are effective because surface area in a waterblock is not as critical as fluid velocity. (I did a quick heat transfer calc) I believe the increased velocity by using a series maze style waterblock with many small channels in series overcomes the loss in flow rate due to the pressure drop over the waterblock. I think velocity in the WB is important not flow rate. To achieve this end I would suggest smaller fluid channels in series rather than different configurations.

04-08-2002, 03:34 AM	#42
Brad Thermophile Join Date: Oct 2001 Location: Nuu Zeeelin Posts: 3,175	jaydee, I was wondering that too \ slipstream, thats all fine but you need to remember that mag drive pumps don't have much psi, so the water flow will slow right down __________________ 2x P3 1100's at 1400, Abit VP6, 2x Corsair 256mb PC150 sticks, 20gb 'cuda ATA-III, 2x 40gb 'cuda ATA-IV in raid 0. 20" Trinitron. No fans 2x 2400+ at 2288mhz (16.0 x 143), Iwill MPX2, 2x Kingmax PC-3200 256mb sticks, 4x 20gb 60gxp in Raid 5 on a Promise SX6000. Asus Ti4200 320/630. Cooled by Water

04-08-2002, 03:59 AM	#43
TiTch Cooling Neophyte Join Date: Mar 2002 Location: London, UK. Posts: 64	Isn't that the result that overclockers.com got with the gemini block with its small chanells, who out performed the larger chanelled maze 2 and single chamber swiftech. __________________ www.gibtek.co.uk

04-08-2002, 07:16 PM	#44
EMC2 Cooling Savant Join Date: Feb 2002 Location: Dark Side of the Moon Posts: 365	Wonders how Roscal's latest number crunch is doing JD - I just thought he was labelling his different test blocks consecutively, lol :shrug: Slipstream - actually the main discussion here was affects of channel geometry to velocity and using CFD software (at least that's been my take on it) Brad - regarding the angled input... that would help lower the inlet restriction and decrease the side of the low flow area at the inlet, but an easier way to address the problem of the low flow in the back 1/3 of the inlet area might be to simply offset the inlet from the die's location so that area is outside where you are wanting maximum heat transfer rates (which is over the die). In the case of a spiral, that kind of fubars things though, so an alternative would be altering the inlet area's geometry to address the problem.

04-08-2002, 11:42 PM	#45
ondaedg Cooling Savant Join Date: Nov 2000 Posts: 130	slipstream brings up a good point. Perhaps someone here can produce two blocks that we can test this out. The blocks would have to be of equal surface area. This would obviously be a constant. The first block would be a high flow block with parallel channels. This could be done by using a design such as Xjinn's or a maze style block with multiple channels running parallel. The second block would be a maze design that is one long maze using narrow channels. The pump to do this should obviously be a fairly high powered pump. I have a 500 gph 7.5 psi pump that would be plenty strong so that it would not be a bottleneck when testing these. To put that into perspective, it can pump water straight up for almost 20 feet. The high velocity of the narrow channeled block may indeed address the subject of this thread which is laminar flow and turbulence. I think it's worth a try and I would be more than happy to help make this work. __________________ ondaedg@procooling.com

04-09-2002, 02:09 AM	#46
Brad Thermophile Join Date: Oct 2001 Location: Nuu Zeeelin Posts: 3,175	emc2, offset the centre, have a turbulant design directly over the core. sounds good? __________________ 2x P3 1100's at 1400, Abit VP6, 2x Corsair 256mb PC150 sticks, 20gb 'cuda ATA-III, 2x 40gb 'cuda ATA-IV in raid 0. 20" Trinitron. No fans 2x 2400+ at 2288mhz (16.0 x 143), Iwill MPX2, 2x Kingmax PC-3200 256mb sticks, 4x 20gb 60gxp in Raid 5 on a Promise SX6000. Asus Ti4200 320/630. Cooled by Water

04-09-2002, 08:55 AM	#47
Dix Dogfight Cooling Savant Join Date: Aug 2001 Location: Stockholm Sweden Posts: 128	Nice to see some calculations/simulationss on this interesting matter. One observation i've made is: All new blocks (maze,spiral.....) have a center inlet above the CPU core. These simulations show that the turbulence on one side of the inlet is wery small. Wouldn't it be better if the inlet is slightly offcenter to have maximum turbulence over the core? Just my 2 cents. __________________ If it ain't broke, fix it. Setup: Dual Duron 1100 \| Voodoo 3 2000 \| Addtronics W8500(WTX) \| Eheim 1250 \| Car radiator \| 2 Innovatech WB \|

07-22-2002, 07:12 AM	#48
Pinkster Cooling Neophyte Join Date: Dec 2001 Location: adelaide, australia Posts: 61	still dont see any of roscals pics damn... still a very informative thread __________________ whats a sig?

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