mayzal

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These are replies submitted by mayzal

@Rouben Rostamian  

Thank you for your assistance. I will try few things and hopefully I could get something.

Greatly appreciate your input.

@Rouben Rostamian  

Thank you for taking your time to assist me.

In the first file I have shared in this question I wrote X1 using (z,t) but I changed it later to (t) only thinking maybe in Maple language I have to write in this way. I returned to (z,t) as you suggested and I'm getting the error:

"Error, (in pdsolve/numeric/match_PDEs_BCs) cannot handle systems with multiple PDE describing the time dependence of the same dependent variable, or having no time dependence"

Note: I agree with you that there is no need for "_dimensionless" so I removed all of them from my variables for easier readability.

variables: 7 {Y[1](z,t), P(z,t), T(z,t), Tw(z,t), v(z), X[1](z,t) and X[2](z,t)}

question4.mw

@C_R 

Thank you for your reply and the time you are taking to assist me.

I think there is no need to specify the velocity because it has a direct relation with the pressure from the pressure drop profile EQN.

In the other software I'm using I didn't include any more boundary conditions. But I tried what you recommended and got the same error:

"Error, (in pdsolve/numeric/process_IBCs) improper op or subscript selector"

question3.mw

@C_R 

Thank you for your reply. I fixed it. The variables are:

P_dimensionless(z,t)

T_dimensionless(z,t)

Tw_dimensionless(z,t)

Y_dimensionless[1](z,t)

velocity_dimensionless(z)

X_dimensionless[1](t)

X_dimensionless[2](t)

Now, however, I'm getting another error:

"Error, (in pdsolve/numeric/process_IBCs) improper op or subscript selector"

question2.mw

@Samir Khan 

Thank you very much for your reply.

@dharr 

I never thought about that because that is too advanced for me. Thank you very much for your reply.

@mmcdara 

Thank you very much for your reply. I didn't know about the events option before.

The file that I shared above is an example. I tried to apply the two methods you shared with the system I'm working on which must be solved using "mebdfi" (I cannot get any results using any other methods). However, I'm getting an error for both methods:

Using the first method I'm getting:

Error, (in dsolve/numeric) parametrized DAE problems cannot be solved with the 'mebdfi' method.

Using the second method I'm getting the same error:

Error, (in dsolve/numeric) problems with discrete variables cannot be solved with the 'mebdfi' method.

Is there a way to apply those methods for systems the must be solved using "mebdfi" numerical method.

Again, thank you very much for your assistance. I'm sure that I would have run in the future into something similar and your approach is very smart so I will keep it in mind.

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