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Active Member
ahmedsal
Posts: 6
Registered: ‎04-17-2012

Steady Coupled Fluid Flow and thermal

374 Views, 6 Replies
04-18-2012 12:44 AM

Hi all

 

I am trying to simulate somthing simple ( two plates and water flowing in the middle) its a coupled steady Fluid and thermal, unfortunatly i can get right results i've been trying to get this thing to work but nada happend... i even modeled and did steady fluid first then steady heat but not working

 

i have inlet outlet and average velocity of 0.015 m/s totla length of the exchanger is 9.5 i am modeling this as 2D so it like a section in the middle of the micro heat exchanger i have the both plate with applied Temp 90C and the water inlet also applied Temp 45C as the water flows in it will have 45 C as T in

 

trouple that i am facing are countles starting with "cant update velocities" to "faild in invoking the process C:\....FRUN03.exe or SRUN10.exe" any way i learned how to fix these things like children learns ABCD..... now i had one last problem

 

when i perform analysis and it take like 30 minute and so i end up with somthing have nothing to do with heat transfer with fluid actualy flowing with a speed it like the fluid is static and not moving at all even if i had the analysis go to 700 s the same thing nada fluid is not moving while the report say somthing else

 

the way that i am visulizing this and please tell me if iam dreaming ( fluid flow in throw the inlet which will have its applied temperature and it will took the fluid ?? s to exit the exchanger and through that we should have  the temperature varies from entrance as min to the exit as max

 

but when the analysis is done all the exchanger is red indicating max temperature and a little bit of temperature varies by the inlet applied temp

 

see i was doubting my input values ( contant and cofecients) i talk to my instructers and guess what they can help me so who ever gona help and if he believe in heaven he/she will be in heaven after a long pleasent life

 

I NEED HELP

 

kindly take a look on the results photos also the .archive file is attahced please feel free to ask anything

 

Sal

 

alright i cant even upload the ach file so go use ansyis get the hell out autodesk and go use ansys because there is no support here " somebody saying that throght out the process to post this msg with the archive file"

 

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Employee
Joey.X
Posts: 259
Registered: ‎06-14-2010

Re: Steady Coupled Fluid Flow and thermal

04-19-2012 07:41 AM in reply to: ahmedsal

Error "cant update velocities" usually comes from improper fluid BCs applied or mesh issue. The archive model is needed to see the root reason. So better to post your archive model for more help.

 

Attached two simple fluid/thermal coupling archive models for your reference.

(a) 2D steady forced convection

(b) 2D transient  forced convection

 

Jianhui Xie, Ph.D
Principal Engineer
MFG-Digital Simulation
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Active Member
ahmedsal
Posts: 6
Registered: ‎04-17-2012

Re: Steady Coupled Fluid Flow and thermal 1 of 2

04-20-2012 06:15 AM in reply to: Joey.X

Hey and thanks for your help

 

kindly find the my model attached to the this replay .... the problem concerning cant update velocities is not occuring not any more but as i said in my orignial post  still it seems that the fluid is static

 

Best

 

Sal

 

PS archive file kinda bif 6 M and the web site wont allow me to uplod this kinda size so it 5 parts

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Active Member
ahmedsal
Posts: 6
Registered: ‎04-17-2012

Re: Steady Coupled Fluid Flow and thermal 2 of 2

04-20-2012 06:18 AM in reply to: ahmedsal

Hey and thanks for your help

 

kindly find the my model attached to the this replay .... the problem concerning cant update velocities is not occuring not any more but as i said in my orignial post  still it seems that the fluid is static

 

Best

 

Sal

 

PS archive file kinda bif 6 M and the web site wont allow me to uplod this kinda size so it 5 parts

Please use plain text.
Employee
Joey.X
Posts: 259
Registered: ‎06-14-2010

Re: Steady Coupled Fluid Flow and thermal 2 of 2

04-20-2012 07:20 AM in reply to: ahmedsal

hi, ahmedsal

 

Thanks for sharing the archive model. However, The atttached .zip files appear not valid archive, I tried using winzip and winrar. 

Could you double check the uploaded archive files or share the whole archive model through dropbox where you set the shared model as public share.

 

Regards,

Jianhui Xie, Ph.D
Principal Engineer
MFG-Digital Simulation
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Active Member
ahmedsal
Posts: 6
Registered: ‎04-17-2012

Re: Steady Coupled Fluid Flow and thermal 2 of 2

04-20-2012 08:31 AM in reply to: Joey.X

this is the archive file

 

http://dl.dropbox.com/u/74675313/Microheat%20Exchanger.ach

 

hopfully this will work

 

thanks again for the help

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Employee
Joey.X
Posts: 259
Registered: ‎06-14-2010

Re: Steady Coupled Fluid Flow and thermal 2 of 2

04-20-2012 10:00 AM in reply to: ahmedsal

The model from dropbox worked for me and I did have a quick look of the modeling and results. 

First of all, the model does have fluid velocity result but I am not sure what your meaning about "fluid is static", please clarify. Since what you did is steady fluid/thermal coupling analysis and a single steady state output is specified, I would assume that you can't see "dynamic fluid". 

Another observation is that you specified fixed nodal velocity in internal nodes, that is generally suspicious but might be okay depending on your physical model and your assumption to converting physical model to simulation model. For forced convection problem, if you specified boundary conditions(such as velocity and temperature), the interior nodal velocity will by driven by boundary conditions and calculated by simulation solver. 

Also as the reminder from a known defect in ASIM/MP, the opening inlet/outlet or any surfaces with flow in/out are not suggested to be setup in parallel to gravity direction because of the missing pressure compensation due to gravity. Otherwise, the unphysical pressure field(ans also affecting velocity field) will be resulted at the vicinity of the opening surfaces. This defect impacts the  model with the BCs you have. 

The last suggestion is using transient fluid /thermal analysis if you like to see dynamic effect of both the fluid and thermal domains. FYI, attached is a video for "Rayleigh-Benard instability  “simulated by ASIM/MP, which is  a typical natural convection problem.(unzip the attached .zip file to get .mp4 video)

 

4-20-2012 12-07-29 PM.png(this is a n image only, click attached zip file for video)

Jianhui Xie, Ph.D
Principal Engineer
MFG-Digital Simulation
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