# FLASH4.6 API

Generated from /asc/asci2/site/flashcode/secure/release_4p6/source/physics/Diffuse/Diffuse_advance1D.F90 with ROBODoc v4.99.8 on Fri Jun 28 16:16:51 2019

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NAME

```  Diffuse_advance1D
```

SYNOPSIS

```  call Diffuse_advance1D(integer(IN)            :: nx,
integer(IN)            :: ny,
integer(IN)            :: nz,
integer(IN)            :: idirection,
integer(IN)            :: bctype(2),
real(IN)               :: del,
real(IN)               :: dt,
real(IN)               :: theta,
real(IN)               :: chi,
real(IN)               :: cond(nx,ny,nz),
real(INOUT)            :: soln(nx,ny,nz),
logical(IN)            :: useCFArray,
real,OPTIONAL, pointer :: ConstFact(:,:,:))
```

DESCRIPTION

```  Subroutine to advance Diffusion in one dimension.

This routine advances a diffusive operator (think heat conduction) in time.

Generic form of the equation a*dV/dt = d/dx(b*dV/dx) + d/dy(b*dV/dy) + d/dz(b*dV/dz)
i.e for Heat conduction, a=rho*Cv, b=conductivity and V=Temp
```

ARGUMENTS

```   nx         : Total grid points along x-direction.

ny         : Total grid points along y-direction.

nz         : Total grid points along z-direction.

idirection : Direction of solve

bctype     : Left and Right boundary condition type.
Supports PERIODIC, OUTFLOW (tested).
DIRICHLET,PNEUMAN (untested).

del        : dx,dy or dz based on direction of solve

dt         : timestep.

theta      : 0.5 CN Scheme, 1.0 Fully Implicit, 0.0 Explicit

chi        : Diffusion coefficient, not used anymore.

cond       : Spatial Conductivity variation (K)

soln       : discretised  variation  of variable to be diffused (input). On Output contains the diffused solution.

useCFArray : Flag to determine if we have ConstFact(:,:,:)

ConstFact  : Spatial distributio of a factor (think rho*cv in heat conduction). !!
```

```  Grid_advanceDiffusion
```  This public API subroutine is so far used only from