Skip to content

USER_MANUAL.md

Latest commit

 

History

History
140 lines (114 loc) · 4.89 KB

USER_MANUAL.md

File metadata and controls

140 lines (114 loc) · 4.89 KB

HeatFlow User Manual

This manual provides a concise guide to configuring and running simulations using the HeatFlow software. The software simulates heat transport using finite difference methods, primarily focusing on the Cattaneo (hyperbolic heat equation) and Fourier models.

Input Files

The simulation is controlled by three main input files located in the inputs/ directory:

  1. param.in: Simulation parameters (time steps, flags, boundary conditions).
  2. mat.in: Material properties.
  3. system.in: Geometry and grid definition.

1. param.in (Simulation Parameters)

This file uses a KEYWORD = VALUE format. Comments can be added using !.

General Settings

Keyword Type Default Description
_RunName String default Name of the simulation run.
IVERB Integer 1 Verbosity level (higher = more output).
ntime Integer 10 Total number of time steps.
time_step Double 1.0 Time step size.
freq Double 1.0 Frequency of the heater.
icattaneo Integer 1 Switch for Cattaneo term (1 = On, 0 = Off/Fourier).
isteady Integer 0 Steady state switch (1 = Steady state, 0 = Transient).
heattime Integer 0 Number of steps for which heating is applied (case 2).
TempDepProp Integer 0 Flag for temperature dependent properties.

Boundary & Conditions

Keyword Type Default Description
iboundary Integer 1 Boundary condition type.
Periodic String '' Periodic boundaries. Contains 'x', 'y', or 'z' (e.g., 'xy').
kappaBound Double 0.0 Global boundary thermal conductivity (sets all planes).
kappaBoundx1...z2 Double 0.0 Specific boundary conductivity (e.g., kappaBoundx1 for x=1 plane).
T_System Double 300.0 Initial system temperature.
T_Bath Double - Global bath temperature (sets all boundaries boundaries).
T_Bathx1...z2 Double T_Bath Specific boundary temperatures.
T_BathCG Double 0.0 Constant gradient bath temperature.
CG_dir String ' ' Direction for constant gradient (e.g., '+x', '-y').
T_BathCC Logical F Scale constant gradient with DeltaT.
BR Double 1.0 Bath Ratio (scaling factor).

Power

Keyword Type Default Description
power_in Double 0.0 Power input for the heater.

Flags (Logical)

All flags default to .False.. Set to .True. (or T) to enable.

  • _Check_Sparse_Full: Check if simulation is sparse or full.
  • _Check_Stability: Perform stability check.
  • _Check_Steady_State: Check for steady state convergence.
  • _WriteToTxt: Enable writing output to text files.
  • _Percentage_Completion: Show progress % in output.
  • _Test_Run: Flag for test runs.
  • _InputTempDis: Load initial temperature distribution from file.
  • _FullRestart: Perform a full restart.

Output Control

Defines the region of the grid to write to output.

Keyword Type Default Description
write_every Integer 1 Write output every N steps.
start_ix, end_ix Integer 1..Nx X-range for output.
start_iy, end_iy Integer 1..Ny Y-range for output.
start_iz, end_iz Integer 1..Nz Z-range for output.

2. mat.in (Material Properties)

Defines the physical properties for each material index used in the system. The file ends with a line containing 0.

Format:

<Material_Index>
keyword = value
...
0
Keyword Description
heat_capacity Specific heat capacity.
kappa Thermal conductivity.
rho Density.
tau Relaxation time (for Cattaneo).
em Emissivity / Parameter (usage depends on physics context).
vel Velocity vector (3 components, e.g., vel = 1.0 0.0 0.0).

Example:

1
heat_capacity = 4200
kappa = 0.541
rho = 997
tau = 1e-12
vel = 0.0 0.0 0.0
0

3. system.in (Geometry/Mesh)

Defines the simulation grid and the material distribution.

Structure:

  1. Grid Dimensions: nx ny nz
  2. Physical Dimensions: Lx Ly Lz
  3. Grid Data: A list of MaterialID:HeaterID for every cell.

The file is read in the order: Z-planes, then Y-rows, then X-columns. Each line in the file (after header) corresponds to one row (X-direction).

Example:

10 10 1
0.01 0.01 0.001

! Z=1, Y=1 Row
1:0 1:0 1:0 1:0 1:0 1:0 1:0 1:0 1:0 1:0
! Z=1, Y=2 Row
1:0 1:0 ...
  • 1:0 means Material ID 1, Heater ID 0 (no heater).
  • 1:1 means Material ID 1, Heater ID 1 (active heater).

Execution

Ensure the inputs/ directory exists with the three required files. Run the executable from the directory containing inputs/.

./ThermalFlow.x

or via fpm:

fpm run --profile release