How to export acoustics data from Fluent to Sysnoise?
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How to export acoustics data from Fluent to Sysnoise? Sysnoise needs 3 types of files from Fluent: .index .asd .data Only one .index and one .data files are needed while the number of .asd files many be more than one. The .asd files contain the "acoustic source data," i.e. information on variables such as pressure, velocity components, and density at every face center on the source face zones written out at the end of every timestep. Each .asd file contains source data for a fixed number of timesteps (as decided by the user, see details below). The .index file contains information about the machine configuration and the set of .asd files The .data file contains coordinates of the face centers on all the source surfaces. Follow these steps to export these files from Fluent: 1) Setup the transient simulation 2) From Define->Models->Acoustics->Models and Parameters Turn on "Export Sound Source Data Only" 3) From Define->Models->Acoustics->Sources Choose the set of source surfaces Choose source data file root name Choose write frequency Choose no. of timesteps per .asd file Click Apply. The .index file is created at this time 4) Run your transient simulation for the number of timesteps required. .asd files are created/appended at the end of every timestep and the index file is modified everytime a new .asd file is created 5) After your transient simulation is done, read in the udf pasted below into your session as a compiled udf. Execute the "write_ac_thread_data" execute_on_demand function. The .data file is created by this. NOTE: In Fluent6.2 you don't need this udf. The .data file can be created using the text command: /define/models/acoustics/write-centroid-info =========UDF===================== #include "udf.h" Domain *domain; char * separator = " "; DEFINE_ON_DEMAND(write_ac_thread_data) { int i,j,tid,sl_mesh; Thread * tptr; char datafn[25]; real ys[3] = {0, 0, 0}; cell_t c; FILE * fp; /* scanf("%s",fn);*/ domain = Get_Domain(1); strcpy (datafn, RP_Get_String("acoustics/base-filename")); strcat (datafn, ".data"); fp = fopen (datafn, "w+"); #if RP_2D fprintf(fp, "(version 2)n"); #endif #if RP_3D fprintf(fp, "(version 3)n"); #endif fprintf(fp,"(n"); for (i=0;i< RP_Get_List_Length("acoustics/writable-threads");i++) { tid = RP_Get_List_Ref_Int("acoustics/writable-threads", i); tptr = Lookup_Thread_All(domain, tid); fprintf(fp,"("); fprintf(fp, "%d%s%d%s%d%s%d%s", tid, separator, THREAD_TYPE(tptr), separator, THREAD_N_ELEMENTS(tptr), separator, (tptr->t0)? DENSITY_METHOD((tptr->t0)):-1, separator); fprintf(fp,")n"); } fprintf(fp,")nn"); for (i=0;i<RP_Get_List_Length("acoustics/writable-threads");i++) { tid = RP_Get_List_Ref_Int("acoustics/writable-threads", i); tptr = Lookup_Thread_All(domain, tid); fprintf(fp,"(%d%s%d%s%d%s(n", SV_CENTROID,separator,tid,separator,THREAD_N_ELEMENTS(tptr),separator); begin_c_loop (c,tptr) { F_CENTROID(ys, c, tptr); for (j=0;j<ND_ND;j++) fprintf(fp, "%7.7g%s",ys[j],separator); fprintf(fp, "n"); } end_c_loop (c,tptr) fprintf(fp,"))n"); } sl_mesh = RP_Get_List_Length("sliding-interfaces"); fprintf (fp, "(sliding-mesh? %s)", sl_mesh? "#t":"#f"); if (sl_mesh) { fprintf (fp,"(time %9.8e)n", CURRENT_TIME); for (i=0;i<RP_Get_List_Length("acoustics/writable-threads");i++) { tid = RP_Get_List_Ref_Int("acoustics/writable-threads", i); tptr = Lookup_Thread_All(domain, tid); fprintf(fp,"(%d%s%d%s%d%s(n", SV_CENTROID,separator,tid,separator,THREAD_N_ELEMENTS(tptr),separator); begin_c_loop (c,tptr) { if (THREAD_TYPE(tptr)!=THREAD_C_GENERIC) { F_AREA(ys, c, tptr); for (j=0;j<ND_ND;j++) fprintf(fp, "%7.7g%s",ys[j],separator); fprintf(fp, "n"); } else { for (j=0;j<ND_ND;j++) fprintf(fp, "%7.7g%s",0.0,separator); fprintf(fp, "n"); } } end_c_loop (c,tptr) fprintf(fp,"))n"); } } fclose(fp); } ==========End of UDF ==================== The document created by LMS describing instructions for importing Fluent data into Sysnoise is below: ------------------------------------------------------------------ FLUENT interface This document contains : Supported versions General description of the FLUENT interface Mesh transfer from FLUENT to SYSNOISE CFD results transfer from FLUENT to SYSNOISE 1. Supported versions. The current revision of FLUENT supported by this interface is: - FLUENT V6.1.18. 2. General description of the FLUENT interface. The interface between FLUENT and SYSNOISE has been implemented in binary format in order to reduce the size of the files containing the CFD results. The .data and the .asd files from FLUENT are directly read into SYSNOISE. The interface contains two links between SYSNOISE and FLUENT, these are described in detail in the following sections. Field points: Information about the location of the data stored in the .asd files can be read in FLUENT format into SYSNOISE. This information does not include any conectivity, only points in the space. CFD Results: Pressure vs time data obtained with FLUENT can be read into SYSNOISE. These CFD results are: 3. Mesh transfer from FLUENT to SYSNOISE 3.1. Reading a field point mesh The command : SYSNOISE> INPUT POINT FILE interface.data FORMAT FLUENT reads the nodes information contained in the FLUENT .data file and adds them to the field point mesh in SYSNOISE. 4. CFD Results transfer from FLUENT to SYSNOISE 4.1. Generating dipole boundary conditions Dipole boundary conditions can be automatically generated from formatted FLUENT .data and .asd files containing CFD results. Dipole boundary conditions can be applied on a part of the mesh or on the the complete model mesh. The SYSNOISE command is: SYSNOISE> GENERATE GENERATE> DISTRIBUTED DIPOLES GENERATE> item_selection GENERATE> FROM PRESSURE TIME FILE 'file.index' FORMAT FLUENT GENERATE> FREQUENCY freq_range GENERATE> MESH FILE 'file.data' FORMAT FLUENT GENERATE> ALGORITHM alg_num TOLERANCE tol AVERAGE aver GENERATE> RETURN The command parameters are : - item_selection A selection of elements has to be made. The generated dipole boundary conditions will be applied on this selection of items. - freq_range Specifies the frequency range for which dipole boundary conditions must be generated. - alg_num Specifies the type of algorithm used for interpolation between CFD and acoustic mesh. For this interface algorithms 0, and 1 are supported. - tol Tolerance applied for interpolation. CFD nodes further than the value of this parameter from the acoustic node taken into consideration at that moment will not be taken into account for interpolation. - aver Number of points in the CFD mesh used to interpolate the pressure value at one node in the acoustic mesh. 4.2. Generating rotating dipole sources Rotating dipole sources can be automatically generated from formated FLUENT .data and .asd files containing CFD results. The pressure data is integrated over the blade surface in order to get the net force on the blade. The blade is divided in segments and one rotating dipole source is created for each segment. The SYSNOISE command is: SYSNOISE> GENERATE FAN GENERATE> FROM FORCE TIME FILE 'file.index' FORMAT FLUENT GENERATE> MESH FILE 'file.data' FORMAT FLUENT GENERATE> NUMBLADES number_of_blades GENERATE> SPEED rotating_speed GENERATE> POSITION fan_center_coordinates GENERATE> VECTOR fan_direction GENERATE> SEGMENTS number_of_segments GENERATE> RETURN The command parameters are : - number_of_blades The total number of blades in the fan. - rotating_speedfreq_range Specifies the rotating speed of the fan in RPM. - fan_coordinates Coordinates of the fan rotation center. - fan_direction Vector pointing in the direction of tha axis of rotation of the fan. - number_of_segments Number of segments in the blade. One source will be genrated for each segment. ------------------------------------------------------------------------------------------------ |
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