In COMSOL we have an option to model heat transfer in solids. For example we have a solid rectangular bar and we want solve 3D heat equation for this geometry. Can we do it in FlexPDE? Any example?

Thanks

6 posts • Page **1** of **1**

In COMSOL we have an option to model heat transfer in solids. For example we have a solid rectangular bar and we want solve 3D heat equation for this geometry. Can we do it in FlexPDE? Any example?

Thanks

Thanks

- zhkhan
**Posts:**11**Joined:**Sat Feb 07, 2015 1:02 am

Absolutely. See the "Samples | Applications | Heatflow" directory of the FlexPDE7 user folder after installing.

FlexPDE is a "scripted finite element model builder". It takes systems of partial differential equations provided by the user and creates a finite element model, builds a mesh, solves the problem and presents graphical output. As such, it has no built-in knowledge of any specific area of application. As long as the user can construct a well-posed PDE system, FlexPDE has a good chance of solving it. Couplings between disparate fields of analysis offer it no difficulty, because it has no concept of what fields "belong together". A partial list of features can be found at http://www.pdesolutions.com/product.html.

If you download our free Lite version, you can peruse over 100 example problems and create small problems of your own design. Downloads can be found at http://www.pdesolutions.com/sdmenu7.html . The User Guide is included in the download and it can also be found online at http://www.pdesolutions.com/help/ .

If you would like to investigate FlexPDE further, we can provide you with a free 30-day trial license to try FlexPDE Professional on your own, larger problems. Information about obtaining a trial can be found at http://www.pdesolutions.com/license.html .

If you decide to purchase FlexPDE, purchasing and pricing information can be found at http://www.pdesolutions.com/pricing7.html .

FlexPDE is a "scripted finite element model builder". It takes systems of partial differential equations provided by the user and creates a finite element model, builds a mesh, solves the problem and presents graphical output. As such, it has no built-in knowledge of any specific area of application. As long as the user can construct a well-posed PDE system, FlexPDE has a good chance of solving it. Couplings between disparate fields of analysis offer it no difficulty, because it has no concept of what fields "belong together". A partial list of features can be found at http://www.pdesolutions.com/product.html.

If you download our free Lite version, you can peruse over 100 example problems and create small problems of your own design. Downloads can be found at http://www.pdesolutions.com/sdmenu7.html . The User Guide is included in the download and it can also be found online at http://www.pdesolutions.com/help/ .

If you would like to investigate FlexPDE further, we can provide you with a free 30-day trial license to try FlexPDE Professional on your own, larger problems. Information about obtaining a trial can be found at http://www.pdesolutions.com/license.html .

If you decide to purchase FlexPDE, purchasing and pricing information can be found at http://www.pdesolutions.com/pricing7.html .

- moderator
**Posts:**766**Joined:**Tue Jan 11, 2011 1:45 pm

I found the 3D_BRICKS+TIME.PDE example but I have a question, which is,

How we will be sure that we are solving the heat equation for a solid not in a square cavity?

How we will be sure that we are solving the heat equation for a solid not in a square cavity?

- zhkhan
**Posts:**11**Joined:**Sat Feb 07, 2015 1:02 am

The COORDINATES section specifies the geometry of your model (see Coordinates in the help index).

You have seven choices. CARTESIAN3, as in 3D_Bricks.pde, selects a "solid" domain. CARTESIAN2 is the default, and selects a planar model.

The parameters you give to your equation will determine what kind of material is contained in your domain.

You have seven choices. CARTESIAN3, as in 3D_Bricks.pde, selects a "solid" domain. CARTESIAN2 is the default, and selects a planar model.

The parameters you give to your equation will determine what kind of material is contained in your domain.

- moderator
**Posts:**766**Joined:**Tue Jan 11, 2011 1:45 pm

Can you please provide a minimal example?

- zhkhan
**Posts:**11**Joined:**Sat Feb 07, 2015 1:02 am

In our USER GUIDE in the HELP system, we have tried to explain the process of constructing a FlexPDE script as clearly as possible, using examples.

One example used there for 3D is the 3D Canister:

TITLE 'Heat flow around an Insulating Canister'

COORDINATES

Cartesian3

VARIABLES

Phi { the temperature }

DEFINITIONS

K = 1 { default conductivity }

R = 0.5 { blob radius }

EQUATIONS

Div(-k*grad(phi)) = 0

EXTRUSION

SURFACE 'Bottom' z=-1/2

LAYER 'underneath'

SURFACE 'Can Bottom' z=-1/4

LAYER 'Can'

SURFACE 'Can Top' z=1/4

LAYER 'above'

SURFACE 'Top' z=1/2

BOUNDARIES

REGION 1 'box'

START(-1,-1)

VALUE(Phi)=0 LINE TO (1,-1)

NATURAL(Phi)=0 LINE TO (1,1)

VALUE(Phi)=1 LINE TO (-1,1)

NATURAL(Phi)=0 LINE TO CLOSE

LIMITED REGION 2 'blob' { the embedded blob }

LAYER 2 k = 0.001 { the canister only }

START 'ring' (R,0)

ARC(CENTER=0,0) ANGLE=360 TO CLOSE

PLOTS

GRID(y,z) ON x=0

CONTOUR(Phi) ON x=0

VECTOR(-k*grad(Phi)) ON x=0

ELEVATION(Phi) FROM (0,-1,0) to (0,1,0) { note 3D coordinates }

END

One example used there for 3D is the 3D Canister:

TITLE 'Heat flow around an Insulating Canister'

COORDINATES

Cartesian3

VARIABLES

Phi { the temperature }

DEFINITIONS

K = 1 { default conductivity }

R = 0.5 { blob radius }

EQUATIONS

Div(-k*grad(phi)) = 0

EXTRUSION

SURFACE 'Bottom' z=-1/2

LAYER 'underneath'

SURFACE 'Can Bottom' z=-1/4

LAYER 'Can'

SURFACE 'Can Top' z=1/4

LAYER 'above'

SURFACE 'Top' z=1/2

BOUNDARIES

REGION 1 'box'

START(-1,-1)

VALUE(Phi)=0 LINE TO (1,-1)

NATURAL(Phi)=0 LINE TO (1,1)

VALUE(Phi)=1 LINE TO (-1,1)

NATURAL(Phi)=0 LINE TO CLOSE

LIMITED REGION 2 'blob' { the embedded blob }

LAYER 2 k = 0.001 { the canister only }

START 'ring' (R,0)

ARC(CENTER=0,0) ANGLE=360 TO CLOSE

PLOTS

GRID(y,z) ON x=0

CONTOUR(Phi) ON x=0

VECTOR(-k*grad(Phi)) ON x=0

ELEVATION(Phi) FROM (0,-1,0) to (0,1,0) { note 3D coordinates }

END

- moderator
**Posts:**766**Joined:**Tue Jan 11, 2011 1:45 pm

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