This file is to control the runtime parameters such as viscosity, conductivity, number of steps, timestep size, order of the timestepping, frequency of output, iteration tolerances, flow rate, filter strength, restart conditions, etc. There are also a number of free parameters that the user can use as handles to be passed into the user defined routines in the .usr file. In addition, it holds the mesh and boundary condition data (unless this has been transferred to the binary .re2 file via the reatore2 tool).
- Overview of the structure of the .rea file
- Section I
- Section II
- Section III
Overview of the structure of the .rea file
- Section I: Parameters, logical switches
This section tells nekton *If the input file reflects a 2D/3D job, *The combination of heat transfer/ Stokes / Navier-Stokes/ steady-unsteady / etc. to be run *The relevant physical parameters *The solution algorithm within NEK5000 to use *The timestep size or Courant number to use, or whether to run variable DT, etc.
- Section II: Mesh Geometry / Boundary Condition Info
NOTE: This section is now contained in a separate .re2 binary file (reatore2 from the tools can be used to convert old .rea files)
This section gives the number of elements, followed by the 4 (8) vertex pairs (triplets) which specify the corner of each two- (three-) dimensional element. A subsection which follows specifies which element surfaces a curved. The exact parameter definitions vary according to the type of curved surface.
- Section III: Output Info
This section specifies what data should be output, including field dumps
****** PARAMETERS ***** 2.610000 NEKTON VERSION 3 DIMENSIONAL RUN (2 or 3) ? PARAMETERS WILL FOLLOW (replace '?' by the number of used parameters)
? LOGICAL SWITCHES FOLLOW (replace '?' by the number of used logical switches)
By default all logical switches are set to false. Make sure that the number in front of IFAVDC and
IFTMSH is at least as large as the number of species you are using.
***** MESH DATA ***** ? ? ? NEL,NDIM,NELV (Replace the ? with NEL, NDIM, and NELV values)
***** CURVED SIDE DATA ***** ? Curved sides follow (Replace the ? with the number of lines to follow)
***** BOUNDARY CONDITIONS ***** ***** FLUID BOUNDARY CONDITIONS ***** ***** THERMAL BOUNDARY CONDITIONS *****
If there are no fluid or no thermal boundary conditions in any given simulation, the word ‘NO’ must precede ‘FLUID’ or ‘THERMAL’ as appropriate.
? RESTART OPTIONS FOLLOW (replace '?' by the number of used restart options; 0 -> no restart)
Initial conditions and drive force data
Not used anymore, use the following dummy lines
0 INITIAL CONDITIONS ***** ***** DRIVE FORCE DATA ***** BODY FORCE, FLOW, Q 0 Lines follow.
***** Variable Property Data ***** Overrides Parameter data. 5 Lines follow. 1 PACKETS OF DATA FOLLOW 0 1 2 GROUP, FIELD, TYPE OF DATA group=0 (default) ifld=1 (field number) type=2 (0: use CONDUCT/RHOCP from the parameters section, 2: user-specified in USERBC)
For every field a separate packet (last 4 lines) must be provided.
If PAR030>0, it suffices to use
***** Variable Property Data ***** Overrides Parameter data. 0 Lines follow.
Specify grid points to monitor the specified variables in time. Example:
***** HISTORY AND INTEGRAL DATA ***** 1 POINTS. Var, Hcode, I, J, K, IEL UV P H 2 2 1 4
- Make sure the parameter LHIS in SIZE is large enough
Logical flags to specify the variables to dump in the field file
***** OUTPUT FIELD SPECIFICATION ***** 7 Lines follow. T COORDINATES T VELOCITY T PRESSURE T TEMPERATURE F TEMPERATURE GRADIENT 1 PASSIVE SCALARS T PS 1
***** OBJECT SPECIFICATION ***** 0 Surface Objects 0 Volume Objects 0 Edge Objects 0 Point Objects