date:20170208

Re: [deal.II] Assemble Righthand Side for vector-valued problem

2017-02-08 Thread Wolfgang Bangerth


On 02/08/2017 01:15 PM, Jaekwang Kim wrote:


I am using deal-ii to analyze Non-newtonian fluids, which varies viscosity.
For example, my viscosity eta is function of (u) field. I am solving
this with iteration method.. (Picard)
After coding, I am testing my code with method of manufacture.

For squared domain, I implemented all boundary condition with my assumed
solution and impose source term also to numerically generate my assumed
solution
however, the problem I got is also follow


While my velocity field is qualitatively similar to manufactured solution,
the pressure field is not following the exact form as seen below figure.
It is very strange that..I can approach u-soltution form while my
pressure does not


In addition , any mesh refinement would not make more accurate solution
now.

If you were me, what would you check more to find out what is problem?


I would make the problem simpler. Do you get the right solution if you 
have a constant viscosity? If you iterate, do you get the solution after 
one iteration?


I will also note that your manufactured solution is symmetric, but your 
computational solution is not. This provides you with a powerful way 
because you don't actually need to look at the convergence, it's enough 
to check that on a *coarse* mesh the solution is *symmetric*. It may be 
that solution is already non-symmetric on 1 cell, or on a 2x2 mesh -- in 
which case you already know that something is wrong. The question then 
is why that is so -- is your rhs correct, for example?


Best
 W.

--

Wolfgang Bangerth  email: bange...@colostate.edu
   www: http://www.math.colostate.edu/~bangerth/

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Re: [deal.II] Assemble Righthand Side for vector-valued problem

2017-02-08 Thread Jaekwang Kim

Thanks, I understand what you meant!!
I fixed it. 

Add up this.. can I ask your intuition for my another problem?

I am using deal-ii to analyze Non-newtonian fluids, which varies viscosity. 
For example, my viscosity eta is function of (u) field. I am solving this 
with iteration method.. (Picard) 
After coding, I am testing my code with method of manufacture. 

For squared domain, I implemented all boundary condition with my assumed 
solution and impose source term also to numerically generate my assumed 
solution 
however, the problem I got is also follow 

While my velocity field is qualitatively similar to manufactured solution, 
the pressure field is not following the exact form as seen below figure. 
It is very strange that..I can approach u-soltution form while my 
pressure does not

In addition , any mesh refinement would not make more accurate solution 
now. 

If you were me, what would you check more to find out what is problem?

2017년 2월 8일 수요일 오후 1시 40분 46초 UTC-6, Wolfgang Bangerth 님의 말:
>
> On 02/08/2017 12:35 PM, Jaekwang Kim wrote: 
> >*/_local_rhs(i) += fe_values.shape_value(i,q) *_/* 
> > 
> > */_rhs_values[q] *_/* 
> > 
> > */_fe_values.JxW(q);_/* 
> > 
>
> rhs_values[q] is a Vector. You need to say which component of it 
> you want to multiply with. (Hint: The correct component is 
> fe.system_to_component_index(i).first). 
>
> Best 
>   W. 
>
> -- 
>  
> Wolfgang Bangerth  email: bang...@colostate.edu 
>  
> www: http://www.math.colostate.edu/~bangerth/ 
>

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Re: [deal.II] Assemble Righthand Side for vector-valued problem

2017-02-08 Thread Wolfgang Bangerth


On 02/08/2017 12:35 PM, Jaekwang Kim wrote:

   */_local_rhs(i) += fe_values.shape_value(i,q) *_/*

*/_rhs_values[q] *_/*

*/_fe_values.JxW(q);_/*



rhs_values[q] is a Vector. You need to say which component of it 
you want to multiply with. (Hint: The correct component is 
fe.system_to_component_index(i).first).


Best
 W.

--

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   www: http://www.math.colostate.edu/~bangerth/

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[deal.II] Assemble Righthand Side for vector-valued problem

2017-02-08 Thread Jaekwang Kim

Hi all, 

I was testing my code, with method of manufactured solution. 

I have a source term, which is vector value, defined as .. 


  template 

  class RightHandSide : public Function

  {

  public:

RightHandSide () : Function(dim+1) {}


virtual void vector_value (const Point ,

   Vector   ) const;


  };


  template 

  void

  RightHandSide::vector_value (const Point ,

Vector   ) const

  {

  

  double n = 0.5 ;

  

  double x =p[0]; double y=p[1];

  

  double f_x=2*x + 7*y - 4*Power(E,3*(Power(-0.5 + x,2) + Power(-0.5 + 
y,2)))*(-0.5 + n)*

  (1 + 2*Power(-0.5 + x,2))*(-0.5 + x)*

  (240. - 320.*x + 448.*Power(x,2) - 256.*Power(x,3) + 128.*Power(x,4) 
- 192.*y +

   320.*Power(y,2) - 256.*Power(y,3) + 128.*Power(y,4))*

  Power(1 + (Power(E,2*(Power(-0.5 + x,2) + Power(-0.5 + y,2)))*

 (64.*Power(0.75 - 1.*x + Power(x,2),2) + 64.*Power(0.75 - 
1.*y + Power(y,2),2)))

/2.,-1.5 + n) - 16.*Power(E,Power(-0.5 + x,2) + Power(-0.5 + y,2
))*(-0.5 + x)*

  Power(1 + (Power(E,2*(Power(-0.5 + x,2) + Power(-0.5 + y,2)))*

 (64.*Power(0.75 - 1.*x + Power(x,2),2) + 64.*Power(0.75 - 
1.*y + Power(y,2),2)))

/2.,-0.5 + n) - 8*Power(E,Power(-0.5 + x,2) + Power(-0.5 + y,2
))*

  (1 + 2*Power(-0.5 + x,2))*(-0.5 + x)*

  Power(1 + (Power(E,2*(Power(-0.5 + x,2) + Power(-0.5 + y,2)))*

 (64.*Power(0.75 - 1.*x + Power(x,2),2) + 64.*Power(0.75 - 
1.*y + Power(y,2),2)))

/2.,-0.5 + n);

  

  double f_y=7*x + 8.*Power(E,3*(Power(-0.5 + x,2) + Power(-0.5 + y,2
)))*(-0.5 + n)*(-0.5 + y)*

  (0.75 - 1.*y + Power(y,2))*(240. - 192.*x + 320.*Power(x,2) - 256.
*Power(x,3) +

  128.*Power(x,4) - 320.*y + 448.*Power(y,2) 
- 256.*Power(y,3) + 128.*Power(y,4))*

  Power(1 + (Power(E,2*(Power(-0.5 + x,2) + Power(-0.5 + y,2)))*

 (64.*Power(0.75 - 1.*x + Power(x,2),2) + 64.*Power(0.75 - 
1.*y + Power(y,2),2)))

/2.,-1.5 + n) + 16.*Power(E,Power(-0.5 + x,2) + Power(-0.5 + y,2
))*(-0.5 + y)*

  Power(1 + (Power(E,2*(Power(-0.5 + x,2) + Power(-0.5 + y,2)))*

 (64.*Power(0.75 - 1.*x + Power(x,2),2) + 64.*Power(0.75 - 
1.*y + Power(y,2),2)))

/2.,-0.5 + n) + 16.*Power(E,Power(-0.5 + x,2) + Power(-0.5 + y,2
))*(-0.5 + y)*

  (0.75 - 1.*y + Power(y,2))*Power(1 +

   (Power(E,2*(Power(-0.5 + x,2) + 
Power(-0.5 + y,2)))*

(64.*Power(0.75 - 1.*x + Power(x,2),
2) + 64.*Power(0.75 - 1.*y + Power(y,2),2)))

   /2.,-0.5 + n);

  

  

  values(0) =  f_x;

  values(1) =  f_y;

  values(2) =  0;

  }
 


and I wanted to assemble RHS in assemble_system function


 template   // Described in Cartesian Coordinate

  void ShearProblem::assemble_system ()

  {

system_matrix=0;

system_rhs=0;



  

  // Variable Coefficient

double shear_rate;

double viscosity;



const MappingQ mapping (degree);

QGauss   quadrature_formula(4*degree+1);


FEValues fe_values (mapping, fe, quadrature_formula,

 update_values|

 update_quadrature_points  |

 update_JxW_values |

 update_gradients);


const unsigned int   dofs_per_cell   = fe.dofs_per_cell;

const unsigned int   n_q_points  = quadrature_formula.size();


FullMatrix   local_matrix (dofs_per_cell, dofs_per_cell);

Vector   local_rhs (dofs_per_cell);


std::vector local_dof_indices (dofs_per_cell);


const RightHandSide  right_hand_side;

  

std::vector  rhs_values (n_q_points, Vector(dim+1));


const FEValuesExtractors::Vector velocities (0);

const FEValuesExtractors::Scalar xvel (0);

const FEValuesExtractors::Scalar pressure (dim);


   

std::vector > symgrad_phi_u (dofs_per_cell);

std::vector  div_phi_u   (dofs_per_cell);

std::vector  phi_p   (dofs_per_cell);


  

std::vector > local_previous_symgrad_phi_u 
(n_q_points);

std::vector  local_previous_solution (n_q_points);



typename DoFHandler::active_cell_iterator

cell = dof_handler.begin_active(),

endc = dof_handler.end();

for (; cell!=endc; ++cell)

  {

fe_values.reinit (cell);

local_matrix = 0;

local_rhs = 0;



right_hand_side.vector_value_list(fe_values.get_quadrature_points(),rhs_values);

fe_values[velocities].get_function_symmetric_gradients 
(previous_solution, local_previous_symgrad_phi_u);

  

  

for (unsigned int q=0; q

[dealii-developers] suffix in extra test outputs

2017-02-08 Thread Denis Davydov

Dear all,

I would like to suggest that we add some sensible info into suffix when 
adding
extra test output. For example

fragile_test.output
fragile_test.output.gcc6
fragile_test.ouptut.gcc4
fragile_test.output.clang8-sierra


When we have fragile tests with 3-4 different outputs, it is easier to 
"read" them if the filenames have some hints.
Ideally if the test fails on some system/compiler, one hopefully would have 
a clue whether or not it's because the test is fragile
or there is some problem indeed.

Note that commit messages may not contain any info on rationale why the 
extra outputs were added.
In the long run, i think it's better to document it in both places -- 
commit message and brief info in filename.

Regards,
Denis

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Re: [deal.II] Fully distributed triangulation (level 0)

2017-02-08 Thread Timo Heister

> Are you willing to share that code, Timo?

Yes, we will be creating a PR for that soon.

> I suspect that if implemented right, it should not be terribly difficult to
> do refinement of the mesh, but because you can't repartition the coarse
> mesh, it will quickly become unbalanced if processors refine differently
> (i.e., in practice, if processors do not all refine globally).

The issue with that is that you would need to update the ghost layer
correctly. Doable, but definitely requires some extra thought.

> Do you implement this by building another class on top of
> dealii::Triangulation so that the base class only stored the coarse mesh
> plus one layer of ghosts, and the derived class is responsible for the
> communication? And then derive another class from DoFHandlerPolicy to deal
> with this triangulation?

Yes. It is derived from parallel::Triangulation (and an alternative to
shared::Tria and distributed::Tria).

-- 
Timo Heister
http://www.math.clemson.edu/~heister/

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Re: [deal.II] ParameterHandler: MultipleSelection of couples

2017-02-08 Thread Franco Milicchio

Thanks, Praveen. 

I could use those, and in my tests that I've done now they work great, but 
this means I won't be able to detect errors automatically. This deal.II 
feature is the best thing, dropping it would be not so cool.

If not possible, I will just do this by hand.

Thank you!
Franco

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Re: [deal.II] ParameterHandler: MultipleSelection of couples

2017-02-08 Thread Praveen C

Hi

In a similar case I have used this function

http://www.dealii.org/developer/doxygen/deal.II/namespaceUtilities.html#a8d799bb35ac16d206818c88e82afbfae

You can use this twice to get the result you want, combined with

http://www.dealii.org/developer/doxygen/deal.II/namespaceUtilities.html#af501c72fdc02dd969cd9d82d0f30642c

Best
praveen

On Wed, Feb 8, 2017 at 9:51 PM, Franco Milicchio  wrote:

> Dear all,
>
> I am using the ParameterHandler class to select multiple parameters and
> lists, but I don't know if I could have something like the following.
>
> What I'd like is to specify multiple parameters that, sort of nested, have
> a string and an integer. As a concrete example, I want to specify stress
> components, or strain, or others. For instance, I'd like to allow "stress",
> "strain", "work", and "power", but only the first two should have an
> additional integer. Take for instance the following (don't mind the syntax,
> please):
>
> subsection dump
>
> set paraview = strain 1, work, stress 8
>
> end
>
> Is there any way I could achieve this with predefined classes? Or should I
> just read a list of strings and parse them myself?
>
> Thanks!
>
> --
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Re: [deal.II] Nonhomogeneous Dirichlet Boundary conditions using a Dirichlet lift

2017-02-08 Thread Praveen C

Hello Giulia

The usual way of applying Dirichlet bc in deal.II essentially does a
lifting approach. If

u = g on boundary

then the lifting is

u_{g,h}(x) = sum_(i on boundary) g(x_i) \phi_i(x)

Did you want to use a different lifting ?

Best
praveen

On Wed, Feb 8, 2017 at 8:38 PM, Giulia Deolmi 
wrote:

> Dear deal.ii users,
>
> is there someone who implemented Nonhomogeneous Dirichlet Boundary
> conditions using a Dirichlet lift?
>
> Thanks a lot in advance,
> Kind regards,
> Giulia
>
> --
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[deal.II] Nonhomogeneous Dirichlet Boundary conditions using a Dirichlet lift

2017-02-08 Thread Giulia Deolmi

Dear deal.ii users,

is there someone who implemented Nonhomogeneous Dirichlet Boundary 
conditions using a Dirichlet lift? 

Thanks a lot in advance,
Kind regards,
Giulia

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Re: [deal.II] Assemble Righthand Side for vector-valued problem

Re: [deal.II] Assemble Righthand Side for vector-valued problem

Re: [deal.II] Assemble Righthand Side for vector-valued problem

[deal.II] Assemble Righthand Side for vector-valued problem

[dealii-developers] suffix in extra test outputs

Re: [deal.II] Fully distributed triangulation (level 0)

Re: [deal.II] ParameterHandler: MultipleSelection of couples

Re: [deal.II] ParameterHandler: MultipleSelection of couples

Re: [deal.II] Nonhomogeneous Dirichlet Boundary conditions using a Dirichlet lift

[deal.II] Nonhomogeneous Dirichlet Boundary conditions using a Dirichlet lift

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