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Question with 'at' operator
Posted Jul 6, 2014, 11:08 p.m. EDT Version 4.3 1 Reply
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Hi guys,
When using Darcy flow module, I want to use a pressure dependent permeability.
Let's say k = k_0*(p/p(at time zero)), and I used 'at' operator to get the pressure at time zero as 'at(1,p)'.
However, it comes to an error saying "The at() operator cannot be used in this context. Failed to evaluate expression.Expression: at(1,mod1.p)"
Could you please give me some clue what's the right way to use the solution at a specific time point?
Regards
When using Darcy flow module, I want to use a pressure dependent permeability.
Let's say k = k_0*(p/p(at time zero)), and I used 'at' operator to get the pressure at time zero as 'at(1,p)'.
However, it comes to an error saying "The at() operator cannot be used in this context. Failed to evaluate expression.Expression: at(1,mod1.p)"
Could you please give me some clue what's the right way to use the solution at a specific time point?
Regards
1 Reply Last Post Jul 7, 2014, 4:36 a.m. EDT
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Posted:
1 decade ago
here is "at" operator's meaning below:
at
• The at operator can access a solution to a time-dependent problem at any time. COMSOL provides the solution at that time using interpolation.
• The first input argument is the time. The second input argument is the expression that you want to evaluate using this solution. For example, at(12.5,u) is the solution at 12.5 s.
• The at operator can only be used during results evaluation, so it should not be used when setting up the model.
at
• The at operator can access a solution to a time-dependent problem at any time. COMSOL provides the solution at that time using interpolation.
• The first input argument is the time. The second input argument is the expression that you want to evaluate using this solution. For example, at(12.5,u) is the solution at 12.5 s.
• The at operator can only be used during results evaluation, so it should not be used when setting up the model.