Diffusivity (transport equation)

Index Diffusivity (transport equation) Ver: 2

DESCRIPTION

Allows the user to modify the value of the diffusivity Df as used in chemically-reacting flow problems. Df is calculated as :

Df = cst * f(T)

By default, there is no temperature dependence, i.e. Df reduces to cst. Default value for cst is 1. When a temperature dependence is requested, POLYFLOW computes a polynomial form :

f(T) = 1 + a1 *T + a2 *T*T + a3 *T*T*T

where 'a1' to 'a3' are parameters. By default, a1 to a3 vanish.

OPTIONS

-1
Upper level menu

The current values are accepted

1
Constant diffusivity

The value of cst is modified

2
Temperature dependence of diffusivity

Gives access to the thermal dependence of the diffusivity as given above

NOTES The units for the parameters are :

Parameter	Mass	Length	Time	Temperature	Mole
Df	-	2	-1	-	-
cst	-	2	-1	-	-
a1	-	-	-	-1	-
a2	-	-	-	-2	-
a3	-	-	-	-3	-
T	-	-	-	1	-

SEE ALSO

transport equation (UM)
create a new sub-task
system of units
material data

-1	Upper level menu
	The current values are accepted
1	Constant diffusivity
	The value of cst is modified
2	Temperature dependence of diffusivity
	Gives access to the thermal dependence of the diffusivity as given above