Model Summary

Nudging Model

The nudging volume is a force volume to adjust the main flow to the measured wind speed.

EQUATION HERE

Where the average is average on the x-y plane, where z is the direction perpendicular to the floor.

Buffer Area

Wind files (wind.dat)

It needs wind.dat, four column file, with time (in hours), wind speed at 100 m, wind direction and ground temperature.

#TIME   WIND(100 m)      WIND(degrees)  TGROUND
0       3.124100        140.194430      309.787196
1       3.929377        165.256440      308.007197
2       4.909175        176.496480      307.237196
3       4.925444        185.826340      305.457198
4       4.780168        195.780750      304.877198

Parameter file

The param.dat contains parameters for the simulation regarding the wind and files.

# parameter file for forensicWindFOAM
windsteps  20       
variable_wind 1     
currentwindstep  0  
nudging  1          
TIrmsbuf  0.05      
continuerun 0

Problem definition

Option	Type	Default	Description
windsteps	Int	0	number of hours/step to read in the wind.dat file, by default hours
currentwindstep	Int	0	current time in the wind
continuerun	Int	0	if continuerun=1, then windtime will be absolute

Run

Decompose the problem in the number of processors specified by decomposeParDict

$ decomposePar

Run in parallel, in this case with 16 cores.

$ mpiexec -np 16 forensicWindFoam -parallel 

Reconstruct the solution

$ reconstructPar

BC

Example of a unsteady boundary condtion on velocity with an square growth and decay in time, with a steady state in the middle.

tank1
    {
        type            uniformFixedValue;
        uniformValue    coded;
        name            tankfire;    
        code 
        #{                                
            vector Unit,Umax;
            const scalar Vpeak =  0.41855; //<-------------------------
            const scalar t0 = 6.5*3600;    // 6:30    start sim
            const scalar ts = 8.5*3600;    // 8:30    start tank fire
            const scalar t1 = 10.5*3600;   // 10:30   end growth phase
            const scalar t2 = 13.5*3600;   // 13:30   star decay
            const scalar t3 = 23.5*3600;   // 23:30   end

            const scalar a = 1/((t1-ts)*(t1-ts));
            const scalar b = 1/((t3-t2)*(t3-t2));
            const scalar small = 0.00001;

            Unit[0] = 1.0;Unit[1]=1.0;Unit[2]=1.0;   
            Umax[0] = 0.0;Umax[1]=0.0;Umax[2]=Vpeak; 

          return vector
       (
         max(x-ts+small,0)/(x-ts) * (min(Unit*a*(x-ts)*(x-ts),Umax)  - Umax*max(x-t2,0)*b*(x-t2) ) 
       );

        #};
    }