i need to find analytical solution to these equations

What are your thoughts? What have you tried? Where are you stuck?

Please be complete. Thank you! ;)
 
Hi Staple,
I have tried to solve the equation by using separation of variables but i am finding it difficult to solve because of the constant Vm.
Thanks for your response.
 
Rewrite the problem as \(\displaystyle \frac{\partial S}{\partial t}+ V_m= D\frac{\partial^2 S}{\partial x^2}\)
\(\displaystyle \frac{\partial (S+ V_mt)}{\partial t}= D\frac{\partial (S+ V_mt)}{\partial x^2}\).

Now let \(\displaystyle U= S+ V_m\) so the equation becomes \(\displaystyle \frac{\partial U}{\partial t}= D\frac{\partial^2U}{\partial x^2}\)
 
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