|
[Sponsors] |
Need help in Implementing Swirl flow velocity - OpenFOAM |
![]() |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
![]() |
![]() |
#1 |
New Member
Adithya Gurumurthy
Join Date: Jun 2017
Posts: 18
Rep Power: 9 ![]() |
Hello all,
I am trying to implement a swirling flow at the inlet of my geometry (inlet is a circular cross-section) for a 3-D steady, turbulent case. I am varying u(z) and u(theta) for a u(r) = 0, for a fixed resultant Umag (0.6 m/s in all my cases). I have tried the following methods: 1. swirlFlowRateInletVelocity - https://github.com/OpenFOAM/OpenFOAM...hVectorField.H 2. cylindricalInletVelocity - https://github.com/OpenFOAM/OpenFOAM...hVectorField.H For the aforementioned methods, I am having an unusual spike in the velocity, where the Umag exceeds its actual intended value at the inlet. I am pasting my inlet BC for U folder for both the methods. //swirlFlowRateInletVelocity INLET { type swirlFlowRateInletVelocity; flowRate constant 1.69e-05; // based on Umag rpm constant 8486; // for Utheta = 0.4243 m/s value uniform (0 0 0); //type fixedValue; //value uniform (0 0.6 0); } //cylindricalInletVelocity INLET { type cylindricalInletVelocity; axis (0 1 0); centre (0 10e-03 0); axialVelocity constant 0.4243; radialVelocity constant 0; rpm constant 8486; // for Utheta = 0.4243 m/s value uniform (0 0 0); } 3. I have also tried implementing through coordinate transformation method using groovyBC for the same inlet condition using the following code INLET { type groovyBC; variables ( "zp=pos().z;" "xp=pos().x;" "r=sqrt(pow(xp,2)+pow(zp,2));" "U_theta=0.4243;" // inputs "U_axial=0.4243;" //inputs "U_radial=0;" // inputs "theta=atan(zp/xp);" "U_x=U_radial*sin(theta)+U_theta*cos(theta);" // conversion to cartesian "U_z=U_radial*cos(theta)-U_theta*sin(theta);" // conversion to cartesian ); valueExpression "vector ( U_x, U_axial, U_z )"; // the cylindrical axis is along Y } For this case, the contour seems wrong and the stream lines do not seem to indicate the swirling motion. I have attached all the plots for your kind perusal. It would be very helpful if anyone could elucidate me on this issue. Thanks in advance. OpenFOAM version: 3.0.1 |
|
![]() |
![]() |
![]() |
![]() |
#2 |
Member
Join Date: Oct 2015
Posts: 63
Rep Power: 10 ![]() |
Hi Adithya!
Even I'm facing a similar issue. I'm getting unphysical results with regards to u(r). I've tried the swirl velocity inlet BC. It would be helpful if someone could post a solution to this problem. |
|
![]() |
![]() |
![]() |
![]() |
#3 |
New Member
Adithya Gurumurthy
Join Date: Jun 2017
Posts: 18
Rep Power: 9 ![]() |
Could someone please shed some light on this issue?
Thanks, Adithya Gurumurthy |
|
![]() |
![]() |
![]() |
![]() |
#4 |
New Member
Kadu
Join Date: Jun 2015
Location: India
Posts: 6
Rep Power: 11 ![]() |
I used this
[Note - my cylinder center is at (0,0,0)] inlet2 { type groovyBC; variables ( "yp2=pos().y;" "zp2=pos().z;" "r2=sqrt(pow(zp2,2)+pow(yp2,2));" "U_ax2=0.5496*pow((1-mag(r2-0.0095)/(1.001*0.0035)),(1/7));" "U_t=0.15*(1-pow((mag(r2-0.0095)/(1.001*0.0035)),2));" "U_tz=-U_t*yp2/r2;" "U_ty=U_t*zp2/r2;" ); valueExpression "vector ( U_ax2, U_ty, U_tz )"; value uniform (0 0 0); } |
|
![]() |
![]() |
![]() |
![]() |
#5 |
New Member
Adithya Gurumurthy
Join Date: Jun 2017
Posts: 18
Rep Power: 9 ![]() |
Thank you Pravin! I am getting realistic results now
|
|
![]() |
![]() |
![]() |
![]() |
#6 | |
Member
Chris Harding
Join Date: Dec 2016
Posts: 76
Rep Power: 9 ![]() |
Quote:
I am new to CFD but I am learning the best I can. In the near future, I will be modeling a nozzle that has significant swirl at the inlet. So, I found your discussion useful. Sadly, I am ignorant to the code that you use in your post. Can you explain each step for me? I know it is a lot to ask, but I will benefit greatly from your tutorial. |
||
![]() |
![]() |
![]() |
![]() |
#7 | |
Senior Member
Kmeti Rao
Join Date: May 2019
Posts: 145
Rep Power: 8 ![]() |
Hi Chris
Quote:
Thank you all in advance Krao |
||
![]() |
![]() |
![]() |
![]() |
#8 | |
Senior Member
Kmeti Rao
Join Date: May 2019
Posts: 145
Rep Power: 8 ![]() |
Quote:
|
||
![]() |
![]() |
![]() |
![]() |
#9 |
New Member
Ali
Join Date: Aug 2019
Posts: 1
Rep Power: 0 ![]() |
Thank you friend for your help
I was trying for Swirlvelocity inlet boundary condition and every time it showed an error for essentioaly " value " and when i added the last line of your description it worked.thank you so much man |
|
![]() |
![]() |
![]() |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
How to calculate swirl velocity or angular velocity in a in-cylinder flow analysis us | tgsankar | Main CFD Forum | 2 | April 26, 2017 16:55 |
Quantifying the swirl in CFX, Swirl Number/Swirl Angle | tauqirnawaz | CFX | 23 | July 24, 2016 22:28 |
Problem with time average tangential velocity in swirl flow. | lakhi | FLUENT | 5 | July 18, 2012 16:28 |
swirl flow | rvndr | FLUENT | 10 | May 30, 2012 02:53 |