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Error: Didn't wake up, abandoning path

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Hi Masoud,

 

Sorry I didn't notice your earlier post. All reactions in the GWB are written as destruction reactions (i.e., Quartz dissolves to form SiO2(aq)). You can set a single kinetic rate law for mineral dissolution or precipitation because the degree of saturation is what controls whether the rate is positive or negative. A general rate law might have the form r = k * A * (1 - Q/K), where k is the rate constant, A is the mineral's surface area (product of mass and specific surface area), Q is the ion activity product, and K is the equilibrium constant. If a mineral is undersaturated then 1 - Q/K is positive, indicating dissolution. On the other hand, if a mineral is supersaturated, however, 1 - Q/K is negative indicating precipitation.

 

You should not set a negative value for the rate constant. If you'd like to set a different rate law depending on whether a mineral is over or undersaturated you can specify a custom rate law. You should still follow the convention of a postive rate indicating dissolution and a negative rate indicating precipitation.

 

Hope that helps get you started. If your model is taking a long time, it might be that your reaction is too fast and is forcing the program to take very small time steps. If that's the case, a kinetic rate law may not be necessary. Another option might be to change some of the parameters in the Config -> Stepping dialog like delxi or delQ. Try taking a look in the GWB Reference Manual for some of these commands.

 

Regards,

 

Brian Farrell

Aqueous Solutions LLC

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