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Showing results 1 to 15 of 15 Search took 0.00 seconds. Search: Posts Made By: Martin Hegedus

Forum: Main CFD Forum January 30, 2012, 17:29

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus Thanks for the clarification. Yup,... Thanks for the clarification. Yup, that was understood. That's why I focused on what goes into the pressure. Plus, the energy equation is not used for your incompressible unheated case. ...

Forum: Main CFD Forum January 30, 2012, 16:11

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus Yes, please do post back! This is interesting. ... Yes, please do post back! This is interesting. LOL, I'm a man of pictures, equations, and plots. This painting with words is just not my cup of tea! :) Just for kicks I've attached the...

Forum: Main CFD Forum January 30, 2012, 13:23

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus I agree with that! So the error of your... I agree with that! So the error of your obstruction is 21% rather than your claimed 8%. Proof: I assume this is how you calculated your overall loss -27%=100*(dp_co-dp_eo)/dp_eo and I'm...

Forum: Main CFD Forum January 30, 2012, 11:25

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus What's the L/D for these sections? Also, I... What's the L/D for these sections? Also, I am uncertain on your calculation of pressure drop percentage. Defininitions Experimental values: dp_eo: delta pressure (head loss) of the section...

Forum: Main CFD Forum January 29, 2012, 16:32

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus I'm going to be straight forward and I am sorry... I'm going to be straight forward and I am sorry if I misunderstand things. And, I know I don't understand the big picture. But it sounds like you believe that only the wall friction contributes to...

Forum: Main CFD Forum January 29, 2012, 15:49

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus I'm assuming your obstruction is a grid of metal... I'm assuming your obstruction is a grid of metal straps with the wide flat side facing the flow vector, this is used for mixing, and you mentioned that the obstruction is 30%. The Cd for a flat...

Forum: Main CFD Forum January 28, 2012, 21:59

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus It is my opinion that on the wall of the channel... It is my opinion that on the wall of the channel in the region of the obstruction (assuming the obstruction goes all the way to the wall) and on the obstruction itself you can not use wall functions....

Forum: Main CFD Forum January 28, 2012, 15:55

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus Have you tried comparing to an experiment without... Have you tried comparing to an experiment without the obstruction?

Forum: Main CFD Forum January 28, 2012, 14:03

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus To me, it sounds like you have TWO things you are... To me, it sounds like you have TWO things you are trying to model. You are trying to model the obstruction and you are trying to model the channel. The obstruction just happens to be in the...

Forum: Main CFD Forum January 28, 2012, 12:29

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus Ooops, I should be clear. Assuming adiabatic... Ooops, I should be clear. Assuming adiabatic wall conditions, the only ingredient added by the obstruction is entropy.

Forum: Main CFD Forum January 28, 2012, 12:08

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus BTW, you mentioned flow channel. Does this mean... BTW, you mentioned flow channel. Does this mean something like a water channel with the top surface exposed to air? If so, there is a lot going on. Much more than I thought when this thread...

Forum: Main CFD Forum January 28, 2012, 11:59

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus Depends if you are using wall functions or not. ... Depends if you are using wall functions or not. In general I do not recommend wall functions for complex geometries. If you don't use wall functions, then start of with y+ equal to 1 taken at about...

Forum: Main CFD Forum January 27, 2012, 20:14

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus Conservation of mass and incompressibility. The... Conservation of mass and incompressibility. The flow into a stream tube must be equal to the flow coming out of the stream tube if the inlet and outlet areas are the same. If the velocity coming...

Forum: Main CFD Forum January 27, 2012, 18:57

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus Maybe it would be good if you posted a picture. ... Maybe it would be good if you posted a picture. The topics of blockage and pressure loss is kind of generic.

Forum: Main CFD Forum January 27, 2012, 18:47

Replies: 39 Pressure drop not correctly predicted Views: 10,603 Posted By Martin Hegedus What's your Mach number and what is the blockage... What's your Mach number and what is the blockage ratio? And is your flow incompressible? If it is incompressible, average velocity coming in has to equal average velocity going out, assuming...

Showing results 1 to 15 of 15

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