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August 19, 2013, 05:02 
transient laminar flow simulation setup

#1 
New Member
Jianguo
Join Date: May 2011
Posts: 9
Rep Power: 7 
Dear SU2 developer and user,
I wish to resolve an unsteady, timeaccurate laminar flow using SU2 CFD module. I want to set up simulation with following options: 1. to use explicit multistage time stepping scheme to perform temporal integration. 2. to print results every time interval of Tint. I have generated mesh and initialized the flow flied. But I do not know how to specify the above options in configuration file. Is there any existing unsteady calculation case with SU2 that I can follow? Thanks 

August 19, 2013, 12:06 

#2  
Super Moderator
Francisco Palacios
Join Date: Jan 2013
Location: Long Beach, CA
Posts: 342
Rep Power: 6 
Using the latest version of SU2 that you can folk from https://github.com/su2code/SU2 . At least, you will need the following parameters in the config file.
%  UNSTEADY SIMULATION % % % Unsteady simulation (NO, TIME_STEPPING, DUAL_TIME_STEPPING1ST_ORDER, DUAL_TIME_STEPPING2ND_ORDER, TIME_SPECTRAL) UNSTEADY_SIMULATION= DUAL_TIME_STEPPING2ND_ORDER % % Time Step for dual time stepping simulations (s) UNST_TIMESTEP= 0.001 % % Total Physical Time for dual time stepping simulations (s) UNST_TIME= 1.0 % % Unsteady CourantFriedrichsLewy number of the finest grid UNST_CFL_NUMBER= 0.0 % % Number of internal iterations (dual time method) UNST_INT_ITER= 200 %  INPUT/OUTPUT INFORMATION % % % Writing solution file frequency WRT_SOL_FREQ= 1000 % % Writing solution file frequency for physical time steps (dual time) WRT_SOL_FREQ_DUALTIME= 10 % % Writing convergence history frequency WRT_CON_FREQ= 1 % % Writing convergence history frequency (dual time, only written to screen) WRT_CON_FREQ_DUALTIME= 10 Best, Francisco Quote:


March 10, 2014, 07:23 
Variable Inlet Velocity

#3 
New Member
nilesh
Join Date: Mar 2014
Location: Kanpur / Mumbai, India
Posts: 27
Rep Power: 4 
Hi,
I am trying to simulate an airfoil starting from t=0 seconds with zero velocity and then increase velocity as a tan hyperbolic function of time. Please help me with specifying such variable velocity boundary condition. Thank You. 

March 10, 2014, 17:24 

#4  
Super Moderator
Francisco Palacios
Join Date: Jan 2013
Location: Long Beach, CA
Posts: 342
Rep Power: 6 
Quote:
void CEulerSolver::BC_Far_Field(CGeometry *geometry, CSolver **solver_container, CNumerics *conv_numerics, CNumerics *visc_numerics, CConfig *config, unsigned short val_marker) that you can find in solver_direct_mean.cpp. In short, the idea is to specify the value for V_infty at each time step. Using config>GetExtIter() you will know what is the current iteration. Cheers, Francisco 

March 31, 2014, 07:14 

#5  
New Member
nilesh
Join Date: Mar 2014
Location: Kanpur / Mumbai, India
Posts: 27
Rep Power: 4 
Quote:
Thanks. Which is the line this this subroutine that is to be modified. Is it 'V_infty = GetCharacPrimVar(val_marker, iVertex)' ? For example, if my function is U=0.8*tanh(t/100) where t is the flow time,what is the exact modification that is to be done? Do I have to write the function or generate velocity at different steps in a file and feed it to the program? Sorry, I do not have any experience in working with C. I will be thankful if you could give me the command/statement. 

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