Thanks for giving me an idea for this!
I will take a look approaches you just mentioned.
Jaekwang
On Wednesday, April 11, 2018 at 12:24:26 AM UTC-5, Jie Cheng wrote:
>
> Hi Jaekwang
>
> One way I can think of is to construct your ConstraintMatrix for Part B
> manually. Iterate over your triangulation, find all the dofs on the target
> boundaries, then use ConstraintMatrix::add_line and
> ConstraintMatrix::set_inhomogeinity to set the BC.
>
> Another method might be putting your calc_tangential_velocity function
> inside New_VelBndValues. I assume this function needs to know the solution,
> triangulation etc. Then you would have to create some references or dealii
> SmartPointers in this class as well.
>
> I hope this helps.
>
> Jie
>
> On Monday, April 9, 2018 at 6:32:28 PM UTC-4, Jaekwang Kim wrote:
>>
>> Hi, all
>>
>>
>> I am always thank you for all guys here in this community.
>>
>>
>> I have a question on the use of VectorTools::interpolate_boundary_values
>> functions
>>
>>
>> Typically we use this function in when we set-up system as in the form
>>
>>
>>
>> VectorTools::interpolate_boundary_values (dof_handler,
>>
>> 1,
>>
>>*Original**_VelBndValues(),*
>>
>>constraints,
>>
>>fe.component_mask(velocities));
>>
>>
>>
>> The red lined functions are usually declared out side of main class.
>>
>>
>> One problem I am interested in now is to (Part A) solve stokes flow with
>> no slip boundary condition on every boundary one time (as step-22), -
>>
>>
>> and then to (Part B) solve same system again with slightly different
>> boundary condition comes from the straight problem
>>
>>
>> If I finish Part A, i have numerical solution of (u,p) linked with dot
>> handler.
>>
>>
>> In (Part B), I post process solutions part A, e.g. I calculated stress
>> value and I calculated tangential velocity of a boundary using Navier slip
>> condition,
>>
>>
>> So, I need to use
>>
>>
>>
>> VectorTools::interpolate_boundary_values (dof_handler,
>>
>> 1,
>>
>>*New_VelBndValues(),*
>>
>>constraints,
>>
>>fe.component_mask(velocities));
>>
>>
>> such that
>>
>>
>>
>> template
>>
>> double
>>
>> New_VelBndValues::value (constPoint ,
>>
>> constunsignedintcomponent) const
>>
>> {
>>
>> Assert (component < this->n_components,
>>
>> ExcIndexRange (component, 0, this->n_components));
>>
>>
>>
>> if(component == 0)
>>
>> *return calc_tangential_velocity (); (Error Here!!)*
>>
>> else
>>
>> return0;
>>
>> }
>>
>>
>>
>>
>> where '*calc_tangential_velocity ();' *is declared in main class, since
>> I should have information of dot_handler and solution vectors.
>>
>>
>> template
>>
>> classStokesProblem
>>
>> {
>>
>> public:
>>
>> StokesProblem (constunsignedintdegree);
>>
>> voidrun ();
>>
>> private:
>>
>>
>>
>> ……
>>
>>
>>
>> *double calc_tangential_velocity ();*
>>
>>
>>
>> BlockVector solution;
>>
>>
>>
>> };
>>
>>
>>
>>
>>
>> Obviously, this method does not work, I mean I cannot compile the code
>> and it shows 'use of undeclared identifier 'calc_tangential_velocity' on
>> the line *(Error Here!!)*
>>
>> I would appreciate any one who comment it. It seems that complier has to
>> know what is that before.
>>
>>
>> Will this be possible in a certain way? How can I go around this problem
>> ?
>>
>>
>> Thanks,
>>
>>
>> Jaekwang
>>
>>
>>
>>
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