The following sections of this chapter are:
TimeBC files (timebc.dat and roughness.dat) are used to specify nodal boundary condition values to FENSAP and DROP3D.
The timebc file is used for inlet, wall and/or exit boundary conditions, and is
created by fensapiceGUI from the values input in the boundary
conditions panel. A custom file can be created using these command line
tools.
FENSAP
Custom timebc files can be set, overriding some settings of the boundary conditions panel, this feature is for expert users and can be enabled by enabling the advanced options in FENSAP-ICE ( → → Show advanced / beta solver options (available at next restart)). The Initial conditions panel will then be accessible in the Conditions panel of FENSAP.
DROP3D
Custom timebc file can be set in the Droplet initial solution panel, by choosing → TimeBC file.
The TimeBC files can be viewed with the Viewmerical
post-processor by using either the TimeBC file input solution type, in the
data-loader panel, or by launching it from the command line with the
viewmerical TIMEBC grid timebc.dat command.
interpTimeBC interpolates the nodal values of a grid/solution
onto the nodes of a grid, writing these values to a timebc file.
A typical case for this command is when running a simulation using a solution from a different flow solver (Fluent, CFX and so on) in which the inlet velocity is not uniform. The source and destination grids are then the same and the boundary condition inlet values are extracted to a TimeBC file.
Table 15.39: interpTimeBC Command
| interpTimeBC GRID1 SOLN1 GRID2 BCLIST FIELD [FIELD FIELD...] [options] |
Will interpolate, in grid1+solution1 values for each node of the specified boundary conditions in grid 2. FIELD is the 4-letter field name of FENSAP/DROP3D. Such as DENS or DRUU, BCLIST can be a single boundary condition, or a comma-separated list of boundary conditions (BC,BC,BC). If BCLIST is -1, all the INLET+WALL+OUTLET will be interpolated. The input and output grids can be the same, will be faster and interpolation-free. |
Table 15.40: Options for DROP3D (Droplets)
| -drop3d |
Converts XVEL,YVEL,ZVEL fields (if specified) to a DROP3D input timebc.dat. |
| -lwc=VALUE |
Adds a LWC (liquid water content) entry to the timebc, with the specified value. |
Table 15.41: Options for DROP3D (Crystals) (TURBO Specific)
| -icc=VALUE |
Adds a ICC (ice crystal content) entry to the timebc file, with the specified VALUE. |
| -dtemp=VALUE |
Adds a constant droplet temperature. |
| -ctemp=VALUE |
Adds a constant crystal temperature. |
| -crystals |
Converts XVEL,YVEL,ZVEL fields (if specified) to a DROP3D CRYSTAL input timebc.dat file. |
| -out=FILENAME |
Specifies the output filename (default is timebc.dat). |
Note: -drop3d and -crystals can be
combined, leading to a droplet+crystal timebc.dat
file.
Example 15.7: Extraction of Droplet Inlet Conditions from an Air Solution File
- interpTimeBC grid.row01 soln.row01 grid.row01 1001 XVEL YVEL ZVEL -drop3d -lwc=0.001
The example above is:
reading the airflow input solution from the source grid.
writing a drop3d timebc file, for the same grid.
extracting the X/Y/Z velocity components from the airflow for the droplet solution.
setting a constant value of 0.001 for the droplet LWC.
Example 15.8: Droplet & Crystal Timebc Input File (TURBO Only)
- interpTimeBC grid.row01 soln.row01 grid.row01 1001 XVEL YVEL ZVEL -drop3d -lwc=0.001 -crystals -icc=0.009 -dtemp=270 -ctemp=270
Sets up a droplet and crystal timebc input file.
genTimeBC generates a timeBC or a sandgrain roughness file
from scratch.
Change GRIDFILE text to: genTimeBC GRIDFILE
"BC,Variable,Expression" [...] [-c3d -fensap -drop3d -rough
-ale]
genTimeBC is a tool enabling to create a timebc (boundary
profile) input file. On a specified GRIDFILE it can define
boundary conditions for one or multiple boundary conditions. The value of each
boundary condition to write in the file, is defined by a tuple
BC,Variable,Expression. The command line can state
multiple tuples. By default, the type of the boundary profile is
-fensap, the tool can be switched to alternate modes
using the other options.
Table 15.42: genTimeBC Command
| genTimeBC GRIDFILE "BC,Variable,Expression" [...] [-c3d -fensap -drop3d -rough -ale] |
Solver mode dependent:
|
Table 15.43: The Expression Can Make Use of the Following Variables
| X Y Z |
Coordinate of the evaluated node. |
| XMIN XMAX YMIN YMAX ZMIN ZMAX |
Minimum/maximum boundaries of the set of nodes belonging to the boundary condition. |
| T |
For time based equations (use -timeStart/Step/End also). |
Time-based file (default is
time = 0, no time step)
| |
Table 15.44: The Variable Parameter Is Ignored for Roughness
| -drop3dConfig=file.par |
Reads the DROP3D configuration and write a suitable timebc.dat file. |
| -bcExtra=BC,Variable,Extra |
For advanced format timebc, last line value specification. |
| -out=timebc.dat |
Sets the custom output file name. |
- interpTurboDropTimeBC
Performs manual row-by-row pitch-averaging interpolation for sequential DROP3D runs.
Note: This is a TURBO feature only.
This tool permits to do row-per-row pitch averaging of solution data, to create a timebc.dat file to use in the next row. The tool will extract conditions from droplet or crystal solutions.
In addition to the pitch-averaged value, the tool permits value injection by modifying the value with an expression. Expressions can read a datafile to construct a 1D inlet-profile dataset.
Table 15.45: Reading a DROPLET Solution
| interpTurboDropTimeBC GRID1 SOLN1 bcGRID1 GRID2 bcGRID2 [-nmix NMIX] [-LWCref VALUE] [-mflux] [-out FILE] [-varChange=FIELD,EXPR] |
This tool will read a DROPLET solution for GRID1 and will interpolate onto GRID2 a timebc.dat file, for use as input to DROP3D. Values are interpolated from BC1 of grid1 to BC2 of grid2. |
Table 15.46: Mandatory Parameters
| -nmix |
Number of sample points to use for the integration (suggested value: 50). |
Table 15.47: Optional Parameters
| -rot X |
DEPRECATED, If the GRID1 solution is in a rotating frame of reference and the GRID2 computation is not, specify the rotation in RPM. (from 2012 onwards, all solutions are in absolute frame of reference). |
| -rotout X |
Specify the GRID2 rotation speed. The timebc.dat written will be added that rotation speed. |
| -rotx/-roty/-rotz |
Specify the rotation axis (default Z). |
| -mflux |
Integrate the velocity by poderating using the mass-flux info. |
| -autoLWC |
if |
| -LWCref / -ICCref |
The reference LWC value default is 0.001 gm/m^3. Values below LWCREF*1.25e-6 will be clipped to zero. |
| -crystal |
Writes a crystal timebc file instead. LWC options will apply to ICC for a hybrid droplet+crystal timebc file, use mergebcs tool. |
| -out FILENAME |
Specify an output file (default is timebc.dat). |
| -varChange=FIELD,EXPR |
Permits to modify the interpolated datafield, either by
fully replacing the value, or mixing it with other values in
the equation. EXPR is an algebraic equation which can be
constructed with the X,Y,Z,R,THETA variables and the current
variable name. For Linux O/S: put the full
|
Table 15.48: Examples
| -varChange=LWC,0.333 |
Forces the LWC to a constant value. |
| '-varChange=LWC,"(R>0.5)*LWC+(R<=0.5)*0.001' |
Forces the LWC to 0.001 if the R coordinate is less than 0.5. |
| '-varChange=TEMP,fileData1D(R,"rTempProfile.txt")' |
Loads the text file rTempProfile.txt
as a 1D linear lookup table. It will change the value of the
variable |
Table 15.49: Interpolation of Droplet Values with Temperature Modification
| interpTurboDropTimeBC grid.row01 droplet.row01 0 grid.row02 0 -nmix 50 -LWCref 0.001 -mflux -out timebc.dat.droplet -rotx -varChange=TEMP, fileData1D(R,"rTempProfile.txt")' |
The rTempProfile.txt file here used will be interpolated as a function of R. The general format of such a file is:
|
If the value of R falls between two entries, a linear interpolation is
computed. See Expression Syntax for reference on the possible
input syntaxes for the varChange second argument.
Table 15.50: Interpolation of Both Drop and Crystals
| interpTurboDropTimeBC grid.row01 droplet.row01 0 grid.row02 0 -nmix 50 -LWCref 0.001 -mflux -out timebc.dat.droplet -rotx |
Interpolate droplets and store in the output file timebc.dat.droplet. |
| interpTurboDropTimeBC grid.row01 crystal.row01 0 grid.row02 0 -nmix 50 -ICCref 0.009 -mflux -out timebc.dat.crystal -rotx |
Interpolate crystals and store in the output file timebc.dat.crystal. |
| mergebcs timebc.dat.droplet timebc.dat.crystal timebc.dat.merged |
Combine the two timebc files in a single timebc.dat.merged. |
mergebcs merges two timebc files defined on the same grid.
The two files must not have any conflicts (different BC-Variable-Node entries).
Typically mergebcs is used to combine separate droplet and
crystal timebc files into a single one.
It can also be used to merge the output of a TimeBC interpolation
(interpTimeBC and a field-specific evaluation with
equations or 1D profiles generated using genTimeBC).
Table 15.51: Usage
| mergebcs TIMEBC_FILE_1 TIMEBC_FILE_2 TIMEBC_OUT |
Merges the output of a TimeBC interpolation
( |
generateRoughnessDat creates a surface sandgrain roughness
input file with values computed from a specified solution file.
The sandgrain roughness file is defined with reference to the airflow (3D)
grid, but if quantities from an ICE3D (surface) solution are to be used, the
solution must be transmogrified onto the 3D grid. Use
soln2soln in -flat mode to do this
(See Examples).
Table 15.52: Creating a roughness.dat File
| generateRoughnessDat GRID [options] |
Creates a roughness.dat file using the specified options. Each successive option may overwrite node values of the previous options. |
Table 15.53: Options
| -bc:ID=VALUE |
Applies a value to all boundaries with ID=VALUE. |
| -range:XMIN,YMIN,ZMIN,XMAX,YMAX, ZMAX=VALUE |
Range will apply to any wall. |
| -solnVar:SOLNFILE:FIELD:>FIELDVALUE:AX,YMAX, ZMAX=VALUE |
From the soln file solution file, read the datafield FIELD. For each node for which the value is greater than FIELDVALUE, the roughness.dat file will contain the value ROUGHVALUE. The < operator is also available. |
| -node:ID=VALUE |
Assign the specified VALUE to the node number ID. |
| -out:FILENAME |
Specify an optional different output file name. |