Click here to donate to keep PhreeqcUsers open
Welcome,
Guest
. Please
login
or
register
.
Did you miss your
activation email
?
1 Hour
1 Day
1 Week
1 Month
Forever
Login with username, password and session length
Forum Home
Login
Register
PhreeqcUsers Discussion Forum
»
Conceptual Models
»
Kinetics and rate controlling factors
»
Integration Time needed to complete KINETICS coupled to TRANSPORT
« previous
next »
Print
Pages: [
1
]
Go Down
Author
Topic: Integration Time needed to complete KINETICS coupled to TRANSPORT (Read 1346 times)
Ucef
Contributor
Posts: 6
Integration Time needed to complete KINETICS coupled to TRANSPORT
«
on:
November 04, 2020, 04:21:19 PM »
Hello everyone,
I am simulating dissolution rate of some silicates and sulfides, but the simulation time becomes extremely long and the integration of rate laws becomes so slow. I noticed that when the integration begins to be slow the following information is added to the Run tab (RK-steps: Bad 0.). This information is underlined in the attached picture. I tried to reduce the number of mixruns by increasing the cell length in the TRANSPORT keyword block, but I noticed that it is not about the numbers of mixruns only but the time needed to complete 1 mixrun is long. Could you help me please I really need to fix that problem.
Thank you
Logged
dlparkhurst
Top Contributor
Posts: 3667
Re: Integration Time needed to complete KINETICS coupled to TRANSPORT
«
Reply #1 on:
November 04, 2020, 09:53:27 PM »
The line with RK-steps appears any time you have KINETICS using the Runge-Kutta integrator (default).
If your simulation is very slow, there could be several reasons. You may have a "stiff" set of rate equations, for which the Runge-Kutta method is not ideal; in this case, you should use the -cvode option of KINETICS.
If -cvode does not help, try integrating over a short time step. If that fails (both RK and cvode), you probably have some inconsistency in your rate definitions. Try eliminating rate definitions to try to determine the problem.
If it succeeds, try progressively longer time intervals. It is possible to have (poorly defined) rate definitions that cannot be integrated past a specific time.
Logged
Print
Pages: [
1
]
Go Up
« previous
next »
PhreeqcUsers Discussion Forum
»
Conceptual Models
»
Kinetics and rate controlling factors
»
Integration Time needed to complete KINETICS coupled to TRANSPORT