[sagarparikh31]

Hello everyone,

I am doing simulation in CFX 15.0 for the turbine blade flutter. In order to get the required results in post processor, I have written several Additional Variables which are aimed to give the fourier coefficients e.g. PressureA0, MeshdispAX0, NormAX0 etc

PressureA0 is defined as [Pa], MeshdispAX0 [m] and NormAX0 as [].

In the domain --> Fluid Models, I have written equations for the respective Additional Variables.

PressureA0 --> Algebraic equations --> PressureA0+StepFinal*(1/StepsProPeriode*cos(-omegaBlade*t*0)*p)

MeshdispAX0 --> MeshdispAX0+StepFinal*(1/StepsProPeriode*cos(-omegaBlade*t*0)*Total Mesh Displacement X)

NormAX0 --> NormAX0+StepFinal*(1/StepsProPeriode*cos(-omegaBlade*t*0)*Normal X ).

In CFX post I was able to see all the variables and also the values, except for the NormAX0. in the variable list NormAX0 is not even indicated.

Can any one help me how to get the NormAX0 in the post, is there any problem because it is dimensionless quantity?

thanks in advance

[Thomas MADELEINE]

Hi,
I have done some simulations with TBR-FT and I also add a few variables of my own. Some of them were dimensionless so I don't think the problem come from here.
I don't know what really is Normal X in your definition of your variable but be sure this variable exist and is initialized when you launch your simulation.

If at one timestep this variable doesn't exist I think it will just erase the NormAX 0. So try to output this thing on CFX-Solver maybe you can figure out where the problem is.

Sorry for not being able to help more on this.

[sagarparikh31]

First of all thanks for the reply and helping me. I have checked what you have recommended

"Normal X" in the formula is an internal valiable, Similarly I have used as "Total Mesh Displacement X". "Normal X" exists by default and so I have used it. As far as initiallization is concerned I have inputs from the steady state analysis and same is used as initial guess for the transient analysis. In the output of the steady state anslysis, there is values for "Normal X".

[Thomas MADELEINE]

ok so if the problem doesn't come from Normal X maybe it comes from NormA0 X :
you use an iterative method to calculate the fourier coefficient : X = X + y
so at the first time step it will calculate X and need to already have a value (or X = undefined + y => error)
Just check that and if it's wrong create a new variable NormA0 X = 0 for one timestep and then pursue with your simulation.

But the thing I don't understand is normally this error should be the same for each of your variable or you already have take care of it.
Moreover, I think if there is a problem like this CFX will just tell you what happened to your variable... so not sure that this is your problem...

Hope you will find a solution

[sagarparikh31]

Yeah I have used iterative method to calculate my variable. As far as setting up of NormAX0 = 0 is concerned, below I am pasting my input file where it shows that NormAX0=0 similar to the other variables. Below you can see I have created number of variables like pressureA0, velocityAX0 etc etc. I am able to get all output except NormAX0.

+--------------------------------------------------------------------+
| Variable Range Information |
+--------------------------------------------------------------------+
+--------------------------------------------------------------------+
| Variable Name | min | max |
+--------------------------------------------------------------------+
| Isothermal Compressibility | 4.85E-06 | 2.81E-05 |
| Thermal Conductivity | 2.61E-02 | 2.61E-02 |
| Courant Number | 1.13E+00 | 5.65E+03 |
| Density | 3.56E-01 | 1.92E+00 |
| Density Derivative wrt Pressure at Constant| 8.35E-06 | 1.42E-05 |
| Static Enthalpy | -5.25E+04 | 1.19E+05 |
| Rothalpy | 2.57E+04 | 9.42E+04 |
| Total Enthalpy | 5.95E+04 | 1.38E+05 |
| Static Entropy | 1.35E+01 | 4.63E+02 |
| Mesh Displacement | 0.00E+00 | 0.00E+00 |
| Total Mesh Displacement | 0.00E+00 | 0.00E+00 |
| Mesh Velocity | 0.00E+00 | 0.00E+00 |
| Pressure | 3.56E+04 | 2.06E+05 |
| Rotational Energy | 2.47E+04 | 5.43E+04 |
| Specific Heat Capacity at Constant Pressure| 1.00E+03 | 1.00E+03 |
| First Blending Function for BSL and SST mod| 2.49E-08 | 1.00E+00 |
| Second Blending Function for SST model | 6.31E-04 | 1.00E+00 |
| Turbulence Eddy Dissipation | 4.74E+04 | 8.29E+09 |
| Turbulence Eddy Frequency | 1.63E+04 | 1.98E+08 |
| Temperature | 2.46E+02 | 4.17E+02 |
| Turbulence Kinetic Energy | 4.06E+00 | 7.74E+03 |
| EigenformRotorBlade1 | 1.46E-02 | 1.11E+01 |
| EigenformRotorBlade2 | 1.46E-02 | 1.11E+01 |
| EigenformRotorBlade3 | 1.46E-02 | 1.11E+01 |
| MeshdispAX0 | 0.00E+00 | 0.00E+00 |
| MeshdispAX1 | 0.00E+00 | 0.00E+00 |
| NormAX0 | 0.00E+00 | 0.00E+00 |
| NormAX1 | 0.00E+00 | 0.00E+00 |
| PressureA0 | 0.00E+00 | 0.00E+00 |
| PressureA1 | 0.00E+00 | 0.00E+00 |
| VelocityAX0 | 0.00E+00 | 0.00E+00 |
| VelocityAX1 | 0.00E+00 | 0.00E+00 |
| Velocity | 7.92E-01 | 5.05E+02 |
| Dynamic Viscosity | 1.83E-05 | 1.83E-05 |
| Eddy Viscosity | 1.02E-08 | 1.40E-02 |
| Wall Scale | -2.42E-09 | 9.79E-04 |
+--------------------------------------------------------------------+

So, I am also trying to fix this problem, but thank you very much for your suggestions and support

[Thomas MADELEINE]

You're welcome, that's the point of this forum, but I am out of ideas here...
You can call the support (ANSYS Germany worked on the TBR-FT), or wait for another one to have an idea here...
Hope you will find and then, can you write on this topic what is the solution please? I am quite interested too?
Thanks

[sagarparikh31]

Yeah Sure, If I will get the solution to this, I will let you know for sure

[sagarparikh31]

Thomas Madeleine, I have found the solution to the mentioned project

Please refer the link below to understand the procedure for the same

http://www.eureka.im/1710.html

[Thomas MADELEINE]

thanks a lot !
the fact that these variable aren't available is quite surprising. I am glad to know that you have figured out your problem.

I hope every thing will get better now.