How can I fix the sign issue in my NDSolve command in Mathematica?

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Discussion Overview

The discussion revolves around a user's issue with the NDSolve command in Mathematica, specifically related to a sign problem in the equations used for mass and energy balances. The focus is on troubleshooting the command to resolve the maximum number of steps reached during computation.

Discussion Character

  • Technical explanation, Homework-related

Main Points Raised

  • The user reports that the NDSolve command works when a negative sign is used in front of a specific term, but believes it should be positive.
  • Another participant suggests that the user simplify the problem and provide the NDSolve expression directly in the post for clarity.
  • A later reply questions whether increasing the MaxSteps parameter might help resolve the issue.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the correct sign to use in the equation, and the discussion remains unresolved regarding the best approach to fix the issue.

Contextual Notes

There may be limitations related to the clarity of the user's problem description and the visibility of the attached Mathematica file, which could affect the troubleshooting process.

burcuugur
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Hi,

I'm trying to model a process by making mass and energy balances using the NDSolve. It reaches the maximum number of steps

It is working when I put "-" sign in front of this [Rho]p*(1 - ec)*\[CapitalDelta]H*D[q[z, t], t] (in 3rd equation) in the NDSolve command. But it should be "+" sign.

I attached the mathematica file.

I would really appreciate some help. This is really important for me.
 

Attachments

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burcuugur said:
I attached the mathematica file.

I don't see the attached notebook. Perhaps something didn't get clicked on. Perhaps there is some restriction involved.

If you could simplify your problem down enough that you could just scrape your NDSolve[] expression, paste it into your post and then edit it to make certain that it was all readable then that might be enough.

If you scrape and paste then carefully check it after you complete the post and edit as necessary to make certain it is all there and readable.
 
Sorry for that. I attached it now.
 
MaxSteps->more?
 

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