Input File Reference¶

All simulation parameters are defined in code_base/inputfile/input_param.txt. The file uses Fortran namelist format.

File Structure¶

The input file has two sections:

Geometry block (free-format, line-by-line)
Namelist blocks (&name ... / format)

Geometry Parameters¶

The geometry is defined by zones in each direction. Each zone has a length, number of control volumes, and power-law exponent for grid stretching.

nzx                          ! number of x-zones (max 7)
xzone(1), xzone(2), ...     ! length of each zone (m)
ncvx(1), ncvx(2), ...       ! number of CVs in each zone
powrx(1), powrx(2), ...     ! power-law exponents (1=uniform, >1=cluster at end, <0=cluster at start)

Same pattern repeated for y (nzy) and z (nzz).

Example (current setup):

Direction	Zones	Lengths	CVs	Exponents	Total
x	1	4.0 mm	400	1 (uniform)	400 cells
y	1	4.0 mm	400	1 (uniform)	400 cells
z	2	0.5 mm + 0.2 mm	10 + 40	-1.5, 1	50 cells

The z-direction uses two zones: a substrate zone (0.5 mm, coarse, clustered toward top) and a powder/build zone (0.2 mm, fine, uniform). Total domain: 4 mm x 4 mm x 0.7 mm.

Grid Stretching

Power-law exponent controls cell clustering:

powr = 1: uniform spacing
powr > 1: cells cluster toward the end of the zone
powr < 0: cells cluster toward the start of the zone (e.g., -1.5 clusters z-cells toward the substrate-powder interface)

Namelist Blocks¶

`&process_parameters` — Surface Laser Source¶

Parameter	Unit	Description
`alaspow`	W	Surface laser power (set to 0 when using volumetric source)
`alaseta`	-	Surface laser absorption efficiency
`alasrb`	m	Laser beam radius (1/e^2)
`alasfact`	-	Gaussian factor (typically 2 for 1/e^2 definition)

`&volumetric_parameters` — Volumetric Heat Source¶

Parameter	Unit	Description
`alaspowvol`	W	Volumetric laser power
`alasetavol`	-	Volumetric absorption efficiency
`sourcerad`	m	Source radius (Gaussian 1/e^2)
`sourcedepth`	m	Source penetration depth

Note

Either surface (alaspow) or volumetric (alaspowvol) source is used. Set the unused one to 0. The volumetric source distributes heat as:

\[q(x,y,z) = \frac{P \cdot \eta \cdot f}{\pi r_s^2 \cdot d_s} \exp\left(-\frac{f}{r_s^2}\left[(x-x_b)^2 + (y-y_b)^2\right]\right)\]

`&material_properties` — Primary Material (C=1)¶

Parameter	Unit	Description	Example
`dens`	kg/m^3	Solid density	8440
`denl`	kg/m^3	Liquid density	7640
`viscos`	Pa*s	Dynamic viscosity (liquid)	0.007
`tsolid`	K	Solidus temperature	1563
`tliquid`	K	Liquidus temperature	1623
`tboiling`	K	Boiling/vaporization temperature	2650
`hlatnt`	J/kg	Latent heat of fusion	290000
`acpa`	J/(kg*K^2)	Solid specific heat coefficient (quadratic term)	0.2441
`acpb`	J/(kg*K)	Solid specific heat coefficient (linear term)	338.59
`acpl`	J/(kg*K)	Liquid specific heat (constant)	709.25
`thconsa`	W/(m*K^2)	Solid thermal conductivity coefficient (linear term)	0.0155
`thconsb`	W/(m*K)	Solid thermal conductivity coefficient (constant term)	5.0435
`thconl`	W/(m*K)	Liquid thermal conductivity (constant)	30.078
`beta`	1/K	Thermal expansion coefficient (for buoyancy)	5e-5
`emiss`	-	Surface emissivity (for radiative loss)	0.3
`dgdtp`	N/(m*K)	dg/dT — thermal Marangoni coefficient	-3.8e-4

Specific Heat Model

Solid specific heat is temperature-dependent: $c_p(T) = a \cdot T + b$ where acpa = $a$, acpb = $b$. The enthalpy-temperature curve is:

Solid ($T \leq T_s$): $H = \frac{a}{2}T^2 + bT$
Mushy ($T_s < T < T_l$): linear interpolation between $H_s$ and $H_l$
Liquid ($T \geq T_l$): $H = H_l + c_{p,l}(T - T_l)$

`&powder_properties` — Powder Layer¶

Parameter	Unit	Description	Example
`layerheight`	m	Powder layer thickness	0.04e-3
`pden`	kg/m^3	Powder density (accounts for porosity)	4330
`pcpa`	J/(kg*K^2)	Powder specific heat (quadratic)	0.2508
`pcpb`	J/(kg*K)	Powder specific heat (linear)	357.7
`pthcona`	W/(m*K^2)	Powder conductivity (linear)	0
`pthconb`	W/(m*K)	Powder conductivity (constant)	0.995

Powder properties apply to cells in the top layerheight of the domain that have not yet been melted (solidfield <= 0.5).

`&numerical_relax` — Solver Parameters¶

Parameter	Unit	Description	Example
`maxit`	-	Max iterations per time step	60
`delt`	s	Time step size	2e-5
`timax`	s	Total simulation time	0.09
`urfu`	-	Under-relaxation factor for u-velocity	0.7
`urfv`	-	Under-relaxation factor for v-velocity	0.7
`urfw`	-	Under-relaxation factor for w-velocity	0.7
`urfp`	-	Under-relaxation factor for pressure	0.7
`urfh`	-	Under-relaxation factor for enthalpy	0.7

`&boundary_conditions` — Thermal Boundaries¶

Parameter	Unit	Description	Example
`htci`	W/(m^2*K)	Convection coefficient on x-faces (west/east)	5
`htcj`	W/(m^2*K)	Convection coefficient on y-faces (north/south)	5
`htck1`	W/(m^2*K)	Convection coefficient on bottom face	5
`htckn`	W/(m^2*K)	Convection coefficient on top face	5
`tempWest`	K	Far-field temperature at west boundary	293
`tempEast`	K	Far-field temperature at east boundary	293
`tempNorth`	K	Far-field temperature at north boundary	293
`tempBottom`	K	Far-field temperature at bottom boundary	293
`tempPreheat`	K	Initial/preheat temperature	293
`tempAmb`	K	Ambient temperature (for radiation)	293

The top surface uses combined convection + radiation: $$q_{loss} = h(T - T_{amb}) + \epsilon \sigma (T^4 - T_{amb}^4)$$

`&output_control` — Output Settings¶

Parameter	Unit	Description	Example
`outputintervel`	steps	VTK output frequency (every N time steps)	50
`case_name`	-	Case identifier (sets output directory name)	'testcase'
`toolpath_file`	-	Path to toolpath file (.crs)	'./ToolFiles/B26.crs'
`species_flag`	-	Enable species transport (0=off, 1=on). When `1`, secondary-material properties are read from `solver_species/inputfile/input_param_species.txt`	0
`predict_flag`	-	Enable field prediction by integer-cell shift (0=off, 1=on)	0

When predict_flag=1, the solver shifts enthalpy, velocity, and pressure fields by an integer number of cells in the scan direction before entering the iteration loop on heating steps (laser on, melt pool present). This provides a better initial guess and reduces iterations by approximately 38% during heating.

`&adaptive_mesh` — Adaptive Mesh¶

Parameter	Type	Description	Default
`adaptive_flag`	integer (0 or 1)	Enable adaptive mesh	0
`amr_local_half_x`	real (m)	Initial half-length of refined region in x	1.0e-3
`amr_local_half_y`	real (m)	Initial half-length of refined region in y	2.0e-4
`amr_dx_fine`	real (m)	Refined cell size	10.0e-6
`remesh_interval`	integer	Regrid every N timesteps	20

When adaptive_flag=1, the mesh is regenerated every remesh_interval timesteps so that the refined region (cell size amr_dx_fine, half-extents amr_local_half_x x amr_local_half_y) follows the laser/melt pool position. Cells outside the refined region use coarser spacing.

The half-extents are lower bounds — at each remesh, half_x = max(amr_local_half_x, current_pool_length) (similarly Y), so the fine zone grows automatically once the melt pool exceeds the user's initial guess. The window centre is anchored on beam_pos AT REMESH TIME (saved as amr_prev_beam_x/y), and downstream consumers (e.g., the CA bbox-uniform clip) use that same anchor to stay aligned with the actual fine-zone footprint regardless of how far the laser has drifted since the last remesh.

Species + AMR¶

When species_flag=1 AND adaptive_flag=1, the species solver lives on its own uniform X/Y grid (cell size = amr_dx_fine, full domain) — independent of the thermal AMR. Each thermal step reprojects thermal fields → species grid (bilinear) and concentration → thermal grid (area-weighted); see Species Transport for details.

`&mechanical_params` — Mechanical Solver¶

Parameter	Type	Description	Default
`mechanical_flag`	integer (0 or 1)	Enable mechanical solver	0
`mech_interval`	integer	Solve mechanical every N thermal steps	10
`mech_output_interval`	integer	Write mechanical VTK every N mechanical solves	5
`mech_mesh_ratio`	integer	FEM grid coarsening ratio vs thermal grid	2

When mechanical_flag=1, the EBE FEM solver computes residual stress and deformation from the thermal field. The FEM grid is coarsened from the thermal grid by mech_mesh_ratio (e.g., 200x200 thermal with ratio=2 gives 100x100 FEM nodes).

CG / Newton tolerances live in a separate file solver_mechanical/inputfile/input_param_mechanical.txt (so material constants and solver knobs don't crowd the global namelist). Defaults:

Knob	Default	Notes
`cg_maxiter_mech`	`2000`	Each CG iter is one EBE matvec; raising past ~2000 rarely helps because Jacobi-preconditioned CG plateaus on the 100× E_solid/E_soft contrast.
`cg_tol_mech`	`1.0e-3`	Relative residual stop. 1e-3 already gives ~180 MPa von-Mises that matches a 1e-4 run within a few %.
`newton_maxiter`	`5`	Outer plasticity iterations.
`newton_tol`	`1.0e-3`	Relative residual stop.

Parallel mode: use bash run.sh <case> <thermal_threads> <mech_threads> to run thermal and mechanical as separate processes. See Mechanical Solver for details.

Input File Reference¶

File Structure¶

Geometry Parameters¶

Namelist Blocks¶

&process_parameters — Surface Laser Source¶

&volumetric_parameters — Volumetric Heat Source¶

&material_properties — Primary Material (C=1)¶

&powder_properties — Powder Layer¶

&numerical_relax — Solver Parameters¶

&boundary_conditions — Thermal Boundaries¶

&output_control — Output Settings¶

&adaptive_mesh — Adaptive Mesh¶