Transient mass diffusion in a semi-infinite solid

1 Transient mass diffusion in a semi-infinite solid 

We will consider transient diffusion of a substance in a semi-infinite body B. At time t = 0, substance A is stored in the body at a concentration cAa. The desired concentration profile cA = cA(x,t) satisfies the following differential equation, under the assumption cD = const 

In analogy to the heat conduction problem, the following conditions are possible at the surface of the body  

As we already know, the solutions for the heat conduction problems in section 2.3.3 can be transferred to the mass diffusion problem, due to the similarity of the differential equations, initial and boundary conditions. The corresponding quantities to heat conduction for mass diffusion are shown in the following table. 

Using these correspondences allows us to write up the solutions to the diffusion problem from the solutions already discussed for heat conduction. 

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