# Convection-Diffusion in a Semi-Infinite Region

Convection-Diffusion in a Semi-Infinite Region

The dimensionless concentrations ( is surface concentration []) in a semi-infinite region are plotted (steady state in orange, transient in blue) up to the space coordinate [].

C=c/

c

0

c

0

M

-3

L

x=

x

max

L

Only one slider is used to adjust the parameters: space [], time [], the flow velocity [], the hydrodynamic dispersion coefficient [] ( is dispersivity []), the first-order reaction rate [], and the frame length [].

x

L

t

T

v

L

-1

T

D=vα

2

L

-1

T

α

L

k

-1

T

x

max

L

The model is described by the partial differential equation C(x,t)+vC(x,t)=DC(x,t)-kC(x,t), subject to the conditions , , .

∂

t

∂

x

∂

x,x

C(0,t)=1

C(∞,t)=0

C(x,0)=0

For a fixed time parameter, the space determines black points on the orange curve and on the blue curve , so that you can see the corresponding numerical values. Smilarly for any parameter the precise values of the steady state and transient dimensionless concentrations are available.

x

C(x,∞)

C(x,t)