How can we specify both spatial and temporal temperature profile on a wall zone?
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In some heat transfer simulations, user will want to impose a temperature profile on a given wall zone that is varying both spatially and temporally. That is, at different times, the spatial profiles are different. Often, user has a tabular data that is obtained from an experiment. Specifying a temporal only OR spatial only can be done using profile. How about both? A UDF has been written to read an input file containing both the spatial and temporal variations of a scalar quantity. The format of this file follows the standard profile format closely and is explained at the end of this file. The UDF contains three sections: ---------------------------------------------------- - ReadFile Type: On-Demand Purpose: To read the input file table - GetData Type: Function Purpose: Interpolate data - Tspec Type: Profile Purpose: Assign data to each face of the face zone How to use it ? ----------------------- - The input file needs to be named as DataFile (can be changed inside the UDF) - Execute the ReadFile on-demand function after reading the case file and before reading the data file. This must be done everytime Fluent is restarted - Hook the Tspec profile function to the temperature field of a wall zone - Iterate as usual The format of input file is given below: ----------------------------------------------------------- - The first line contains the NPtsTm (number of time steps points) and NPtsData (number of data points) - Next line is a blank - Next NPtsTm lines contain the time data - Next line is a blank - Next NPtsData lines contain the x-coordinates data - Next line is a blank - Next NPtsData lines contain the y-coordinates data - Next line is a blank - Next NPtsData lines contain the z-coordinates data - Next line is a blank - Next NptsData lines contain the first scalar data at time#0 - Next line is a blank - Next NptsData lines contain the first scalar data at time#1 - ... so on ... until the last time data is given ------------------------------------------------- #include "udf.h" int NPtsTm,NPtsData; int DataIsRead = 0; float *tmarr,*xarr,*yarr,*zarr,**Tarr; DEFINE_ON_DEMAND(ReadFile) { int n,i; float data; FILE* fp; fp = fopen("DataFile","r"); if ( fp!=NULL ) Message("Reading file n"); else Message("Error in opening file n"); fscanf(fp,"%d %dn",&NPtsTm,&NPtsData); Message("n"); Message("There are %d time entries and %d spatial entriesn",NPtsTm,NPtsData); /* Dynamic allocation for 1D array */ tmarr = (float *) malloc(NPtsTm*sizeof(float)); xarr = (float *) malloc(NPtsData*sizeof(float)); yarr = (float *) malloc(NPtsData*sizeof(float)); zarr = (float *) malloc(NPtsData*sizeof(float)); /* Dynamic allocation for 2D array */ { float *temp; temp = (float * ) malloc(NPtsTm*NPtsData*sizeof(float)); Tarr = (float **) malloc(NPtsTm*sizeof(float *)); for(n=0;n<NPtsTm;n++) Tarr[n] = temp + n*NPtsData; } if ( (tmarr==NULL)||(xarr==NULL)||(yarr==NULL)||(zarr==NULL)||(Tarr==NULL) ) Message("Memory allocation error n"); fscanf(fp,"n"); Message("n"); Message("The following is the %d time entriesn",NPtsTm); for ( n=0;n<NPtsTm;n++ ) { fscanf(fp,"%f n",&data); tmarr[n] = data; Message(" %fn",data); } fscanf(fp,"n"); for ( i=0;i<NPtsData;i++ ) { fscanf(fp,"%f n",&data); xarr[i] = data; } fscanf(fp,"n"); for ( i=0;i<NPtsData;i++ ) { fscanf(fp,"%f n",&data); yarr[i] = data; } fscanf(fp,"n"); for ( i=0;i<NPtsData;i++ ) { fscanf(fp,"%f n",&data); zarr[i] = data; } for ( n=0;n<NPtsTm;n++ ) { fscanf(fp,"n"); for ( i=0;i<NPtsData;i++ ) { fscanf(fp,"%f n",&data); Tarr[n][i] = data; } } DataIsRead = 1; fclose(fp); /* Output check */ Message("n"); Message("The following is the %d coordinate entriesn",NPtsData); for ( i=0;i<NPtsData;i++ ) { Message(" %f %f %fn",xarr[i],yarr[i],zarr[i]); } for ( n=0;n<NPtsTm;n++ ) { Message("n"); Message("The following is scalar data for time entry # %dn",n); for ( i=0;i<NPtsData;i++ ) { Message(" %fn",Tarr[n][i]); } } } /*----------------------------------------------------------------------------*/ float GetData(float xf, float yf, float zf, float tm) { int n,nL,nU,i; float tmL,tmU,data,dataL,dataU,sf,smin; tm += 1.0e-7; /* Find the time bracket */ nL = 0; nU = 1; tmL = tmarr[nL]; tmU = tmarr[nU]; for ( n=0;n<NPtsTm;n++ ) { if ( (tm>=tmarr[n])&&(tm<=tmarr[n+1]) ) { nL = n; nU = n+1; tmL = tmarr[nL]; tmU = tmarr[nU]; break; } } /* Find data at the lower and upper time bound */ smin = 1.0e30; dataL = 0.0; dataU = 0.0; for ( i=0;i<NPtsData;i++ ) { sf = sqrt( pow((xarr[i]-xf),2) + pow((yarr[i]-yf),2) + pow((zarr[i]-zf),2) ); if ( sf<=smin ) { smin = sf; dataL = Tarr[nL][i]; dataU = Tarr[nU][i]; } } /* Interpolate between lower and upper time values */ data = dataL + ( tm - tmL )/( tmU - tmL )*( dataU - dataL ); return data; } /*----------------------------------------------------------------------------*/ DEFINE_PROFILE(Tspec,tf,pos) { face_t f; float tm,xf[ND_ND]; tm = RP_Get_Real("flow-time"); begin_f_loop(f,tf) { F_CENTROID(xf,f,tf); F_PROFILE(f,tf,pos) = GetData(xf[0],xf[1],xf[2],tm); } end_f_loop(f,tf) } |
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