Defining thermal convection for a cohesive element

You can define convective heat transfer with gap flow as well as thermal convection between the gap fluid and both the top and bottom surfaces of a coupled temperature-pore pressure cohesive element.

Thermal convection modeling using coupled temperature-pore pressure cohesive elements:

  • can be performed in coupled pore fluid diffusion/stress analyses (Coupled pore fluid diffusion and stress analysis);
  • can also involve convective heat transfer between the gap fluid and both the top and bottom surfaces of a cohesive element; and
  • can be specified by a material model.

This page discusses:

See Also
In Other Guides
*DENSITY
*SPECIFIC HEAT
*CONDUCTIVITY
*GAP CONVECTION
*MATERIAL

ProductsAbaqus/StandardAbaqus/CAE

Modeling thermal convection together with gap fluid flow within a cohesive element

The thermal convection contributes toward the energy balance. The energy equation is given by:

ρfcf(dθ),t+ρfcf∇⋅(dqθ)−∇⋅(dk∇θ)−ρfcf[ct(pi−pt)+cb(pi−pb)]−h(θ−θt)−h(θ−θb)=0,

where

ρf
is the fluid density,
cf
is the specific heat of the fluid,
k
is the conductivity of the fluid,
h
is the heat convection coefficient,
θ
is the temperature of the gap flow,
θt
is the temperature on the top surface, and
θb
is the temperature on the bottom surface.
All of the other variables (such as q, d, pi, pt, pb, ct, and cb) are defined in Defining the constitutive response of fluid transitioning from Darcy flow to Poiseuille flow.

Specifying fluid density

You can define the gap fluid density.

Input File Usage

DENSITY, PORE FLUID

Abaqus/CAE Usage

Specifying the gap fluid density is not supported in Abaqus/CAE.

Specifying specific heat of the fluid

You can define the specific heat of the pore fluid in a porous medium.

Input File Usage

SPECIFIC HEAT, PORE FLUID

Abaqus/CAE Usage

Specifying the specific heat of the pore fluid in a porous medium is not supported in Abaqus/CAE.

Specifying conductivity of the fluid

You can define the conductivity of the pore fluid in a porous medium.

Input File Usage

CONDUCTIVITY, PORE FLUID

Abaqus/CAE Usage

Specifying the conductivity of the pore fluid in a porous medium is not supported in Abaqus/CAE.

Specifying heat convection between the fluid and both the top and bottom surfaces

The heat convection coefficient is defined as

h=Nu2kd,

where Nu is the Nusselt number. You can specify the Nusselt number as a function of temperature and field variables.

Input File Usage

Use the following option to define a constant flux solution for convective heat transfer (Nu=8.235):

GAP CONVECTION, TYPE=FLUX

Use the following option to define a constant temperature solution for convective heat transfer (Nu=7.54):

GAP CONVECTION, TYPE=TEMPERATURE

Use the following option to specify the Nusselt number as a function of temperature and/or field variables:

GAP CONVECTION, TYPE=TABULAR

Abaqus/CAE Usage

Property module: material editor: OtherPore FluidGap Convection: Type: FLUX, TEMPERATURE, or TABULAR