CFD Online Discussion Forums

CFD Online Discussion Forums - Main CFD Forum http://www.cfd-online.com/Forums/ Topics that do not have a dedicated forum below. en Wed, 08 Sep 2010 11:45:03 GMT vBulletin 60 http://www.cfd-online.com/Forums/images/misc/rss.jpg CFD Online Discussion Forums - Main CFD Forum http://www.cfd-online.com/Forums/ Good Universities for MS in CFD (in US and UK both) http://www.cfd-online.com/Forums/main/79899-good-universities-ms-cfd-us-uk-both.html Wed, 08 Sep 2010 08:52:26 GMT Hello guys, I am looking forward for MS (Fall 2k11). Can you please suggest me the universities in US that have research interests in the field of... Hello guys, I am looking forward for MS (Fall 2k11). Can you please suggest me the universities in US that have research interests in the field of CFD. ]]> Main CFD Forum vinaynitrkl http://www.cfd-online.com/Forums/main/79899-good-universities-ms-cfd-us-uk-both.html CFD jobs for non american people http://www.cfd-online.com/Forums/main/79876-cfd-jobs-non-american-people.html Tue, 07 Sep 2010 13:46:37 GMT Hello,

My problem is simple. I'm french and I'll graduate by the end of the year. I would like to find the best cfd field to do my graduate research project since I want to find a job in the US. So what kind of job do you know far from aerospatial/defense and governmental related jobs ?

Thank you,
Clément ]]> Main CFD Forum Equilibrium http://www.cfd-online.com/Forums/main/79876-cfd-jobs-non-american-people.html FS3D Code http://www.cfd-online.com/Forums/main/79874-fs3d-code.html Tue, 07 Sep 2010 12:45:19 GMT Hi every one; Is there anyone who uses FS3D (free surface 3D) code for CFD analysis? Is this code available on the internet? I searched but I... Hi every one;
Is there anyone who uses FS3D (free surface 3D) code for CFD analysis? Is this code available on the internet? I searched but I couldn't find any information about this code.
I will be so glad if you could help me. Thanks ]]> Main CFD Forum invadoria http://www.cfd-online.com/Forums/main/79874-fs3d-code.html Two-Way_coupling_turbulent_flow http://www.cfd-online.com/Forums/main/79864-two-way_coupling_turbulent_flow.html Tue, 07 Sep 2010 08:50:50 GMT Dear My Friends Is there any one to help me with the source terms that are appeared to fluid X, Y momentum and k-e equations ? I read about... Dear My Friends

Is there any one to help me with the source terms that are appeared to fluid X, Y momentum and k-e equations ?
I read about these source terms in some article like Sommerfeld and Ahmadi.

But I want to know about the procedure of evaluating source terms and how can I calculate them in process of program? ]]> Main CFD Forum mmmahdavimanesh http://www.cfd-online.com/Forums/main/79864-two-way_coupling_turbulent_flow.html KIVA4 postprocessor - Ensight CFD http://www.cfd-online.com/Forums/main/79861-kiva4-postprocessor-ensight-cfd.html Tue, 07 Sep 2010 07:30:26 GMT Hi, Can someone help me with how to make the KIVA4 output compatable with Ensight CFD 3.0? Hi,

Can someone help me with how to make the KIVA4 output compatable with Ensight CFD 3.0? ]]> Main CFD Forum geothokar http://www.cfd-online.com/Forums/main/79861-kiva4-postprocessor-ensight-cfd.html KIVA4-compost.i http://www.cfd-online.com/Forums/main/79860-kiva4-compost-i.html Tue, 07 Sep 2010 07:25:29 GMT Hi,

Can some one send me the 'compost.i' file in KIVA4?

I can't find this input file in the KIVA source codes I obtained. My compiler always exits after checking for this file in stdlbls subroutine. ]]> Main CFD Forum geothokar http://www.cfd-online.com/Forums/main/79860-kiva4-compost-i.html How to clarify vortex shedding of airfoil http://www.cfd-online.com/Forums/main/79859-how-clarify-vortex-shedding-airfoil.html Tue, 07 Sep 2010 07:05:35 GMT Dear all, I have carried out a LES simulation for 2D airfoil in big angle of attack. Power Spedtra of CL CD and velocities of some points in wake... Dear all,

I have carried out a LES simulation for 2D airfoil in big angle of attack. Power Spedtra of CL CD and velocities of some points in wake showed that there are many peaks from tens to hundreds for frequency.
As we know that the typical St=0.2, But how can I clarify the vortex shedding? how to define the frequency for the flow as there are so many peaks.

Thanks all.

Yang ]]> Main CFD Forum David.yang http://www.cfd-online.com/Forums/main/79859-how-clarify-vortex-shedding-airfoil.html Difference between VOF Schemes http://www.cfd-online.com/Forums/main/79856-difference-between-vof-schemes.html Tue, 07 Sep 2010 06:26:58 GMT Hi every one I am working on modeling two phase flow inside the mixing chamber with two separate inlets for water and air and one discharge... Hi every one

I am working on modeling two phase flow inside the mixing chamber with two separate inlets for water and air and one discharge outlet.

I have used different explicit (georeconstruct, CICSAM) and implicit (HIRC, 2nd UW) schemes for simulations. I have measure the water cross-sectional thickness at the discharge for these scheme and got varied result for same inputs. For low gas-liquid ratio the difference is small but at high gas-liquid ratio the difference is more.

Can somebody help in explaining these scheme as how they work? so that i can comment on the results.

Thanks in advance ]]> Main CFD Forum ash-khan http://www.cfd-online.com/Forums/main/79856-difference-between-vof-schemes.html thermal rejection limit of fluid http://www.cfd-online.com/Forums/main/79829-thermal-rejection-limit-fluid.html Mon, 06 Sep 2010 05:32:51 GMT Dear all, in thermal-fluid analysis, is there a limit on the heat rejection by the fluid it can achieve please? what theory, or parameter... Dear all,

in thermal-fluid analysis, is there a limit on the heat rejection by the fluid it can achieve please?

what theory, or parameter should i read on? conservation of energy?

i believe that, for a given amount of heat source, the fluid which has a fix flowrate and temperature flowing through cooling channel of fix dimensions is only able to reject a certain amount of heat from the heat source. As the heat source increases, the fluid can only reject a max. limit from the heat source and stay constant.

Look forward to hear of any comments/ideas. ]]> Main CFD Forum mactech001 http://www.cfd-online.com/Forums/main/79829-thermal-rejection-limit-fluid.html Radioss-CFD http://www.cfd-online.com/Forums/main/79823-radioss-cfd.html Sun, 05 Sep 2010 21:56:47 GMT Does anyone knows what happend to this code (Radioss-CFD) ??? i know Radioss code (solver ) from Altair engineering ( took with Mecalog) but... Does anyone knows what happend to this code (Radioss-CFD) ???

i know Radioss code (solver ) from Altair engineering ( took with Mecalog)
but Radioss was crash code not cfd.... does anyone knows the story???

thanks ]]> Main CFD Forum eleazar http://www.cfd-online.com/Forums/main/79823-radioss-cfd.html 2D Finite Volume Method - Please help http://www.cfd-online.com/Forums/main/79809-2d-finite-volume-method-please-help.html Sun, 05 Sep 2010 02:10:38 GMT Hi Everyone,

I am trying to solve a 2D shocktube problem in a 2D, cell-centered, First order finite volume framework.

I coded Roe's scheme using the sample code given at I do like cfd site, but after I run the code nothing seems to happen to density and pressure, even though I let the code run for really long time. I don't see any initial structure (shock, contact, expansion) at the interface of left and right sections of the grid. Whle for u and v, there're some really strong disturbances only in some cells.

I have a feeling that either I have not set up my normal vectors correctly or that my choice of left and right states at a given interface is not correct.

* In the first order cell-centered FVM, we define values at the center of the cell, and use the same values at the cell-interface. In second-order, we will reconstruct the variation of primary variables to obtain their interface values from cell-centers. Is that correct?

* Now, in a 2D FVM method, we solve Riemann Problem at every interface, right? Consider a left face of cell (i,j). Now the When I am solving a Riemann problem on this left interface, is the following correct?
Cell : (i,j)
Interface: Left
Left state for above interface: Left Interface Value of cell (i,j)
Right state: Right Interface value of Cell (i-1,j)

Similarly,
for the same cell, but
Interface: Bottom
Left state: Bottom Interface Value of cell (i,j)
Right State: Top Interface Value of cell (i,j-1)

Is above correct?

Thank you very much. Please let me know if you need further info.
PS: I am actually kinda very frustrated b/c, I have am stuck at 2D FVM, what a shame! :(( ]]> Main CFD Forum WatchFirefly http://www.cfd-online.com/Forums/main/79809-2d-finite-volume-method-please-help.html Turbulence model for mixing problem??? http://www.cfd-online.com/Forums/main/79808-turbulence-model-mixing-problem.html Sun, 05 Sep 2010 00:09:53 GMT Hello all, I am trying to simulate air/fuel mixing in a combustion chamber. I need to specify a turbulence model (RANS) for this. My questions are ... Hello all,
I am trying to simulate air/fuel mixing in a combustion chamber. I need to specify a turbulence model (RANS) for this. My questions are

1) Which model would be better suited for such kind of simulation?? RNG-k-eps or SST-kW or any other??

2) About near wall treatment: I suppose k-w does not need a wall function as it can handle near wall flow on its own, am i right??

3) For RNG k-eps i will have to give some near wall function. Now my dialemma is for coarse mesh (y+ > 30) i have to specify wall function if i use standard k-eps model (which is High Re model in OpenFoam). But what if i use Low Re model like Launder-Sharma?? What about RNG (is it low Re or high Re)??

4) For mixing problem like this, how much importance the "near wall flow" have??? I am currently doing only cold flow simulations.

Thank you. ]]> Main CFD Forum nileshjrane http://www.cfd-online.com/Forums/main/79808-turbulence-model-mixing-problem.html long pipe study http://www.cfd-online.com/Forums/main/79800-long-pipe-study.html Sat, 04 Sep 2010 15:42:43 GMT Hi friends,
I got a question,
I have to study the head loss along a 1 km 8" pipe and to do so, I would face the problem by dividing the pipe into several parts and the result of one section pipe will be the input of the next one and so on till getting the final head loss.

Could anybody tell me how to take those results and use them as an input of the next section pipe?

every section pipe is stored into a different file.

thanks ]]> Main CFD Forum andresinho http://www.cfd-online.com/Forums/main/79800-long-pipe-study.html Numerical Solution for one dimension linear wave problem http://www.cfd-online.com/Forums/main/79797-numerical-solution-one-dimension-linear-wave-problem.html Sat, 04 Sep 2010 10:27:58 GMT I am a newbie in CFD.I need to solve the one dimension linear wave problem.I have found some source from wiki here and wikipedia.... I am a newbie in CFD.I need to solve the one dimension linear wave problem.I have found some source from wiki here and wikipedia.
http://www.cfd-online.com/Wiki/Linea...Runga-Kutta.29

I need to solve using 6th compaq scheme,1st order upwind scheme,2th maccormack scheme and lax-wendroff scheme.And compare the results of this different schemes.The time derivative needs to be solve using 4th runge-kutta method.Can anybody explain more on how to do the numerical solution?Thanks.And,how to integrate the 4th runge-kutta into the equation?
I need more help and resource on how to do it.

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]]> Main CFD Forum cxcxcx0505 http://www.cfd-online.com/Forums/main/79797-numerical-solution-one-dimension-linear-wave-problem.html Errors n Gabit http://www.cfd-online.com/Forums/main/79793-errors-n-gabit.html Sat, 04 Sep 2010 07:56:21 GMT While creating a skin surface I encountered an error which says : self instructing or cusping edges found . how to rectify it? While creating a skin surface I encountered an error which says : self instructing or cusping edges found . how to rectify it? ]]> Main CFD Forum aayushtewari01 http://www.cfd-online.com/Forums/main/79793-errors-n-gabit.html