# How to manage materials

# Introduction

Three types of materials are defined: fluid materials, solid materials, and thermal interface materials (TIM). A material can be assigned to a solid region, fluid region, or interface by selecting it from the material list or by defining a new one. The list of materials can be managed through the library page. This page contains a list of predefined materials, but you can define your materials as well. The predefined materials cannot be edited by anyone, your custom materials can.

Property | Material type | |||
---|---|---|---|---|

Name | Unit | Solid | Fluid | TIM |

Density $\rho$ |
$kg/m^3$ | |||

Dynamic viscosity $\mu$ |
$kg/(m\cdot s)=Pa\cdot s$ | |||

Specific heat capacity $C_p$ |
$J/(kg\cdot K)$ | |||

Absorption coefficient $\alpha$ |
$m^{-1}$ | |||

Thermal conductivity $\kappa$ |
$W/(m\cdot K)$ | |||

Coefficient of thermal expansion $\beta$ |
$K^{-1}$ | |||

Thickness $R_d$ |
$m$ | |||

Resistivity |
$\Omega \cdot m$ | |||

Thermal resistance $R_{th}$ |
$K/W$ |

# Solids

## Density

- constant value at a reference temperature
- a polynomial function of temperature where a maximum of 8 coefficients can be provided
- table containing temperature and corresponding parameter value of the material at the specified temperature

## Specific heat capacity

- constant value at a reference temperature
- a polynomial function of temperature where a maximum of 8 coefficients can be provided
- table containing temperature and corresponding parameter value of the material at the specified temperature

## Thermal conductivity

- constant value at a reference temperature
- a polynomial function of temperature where a maximum of 8 coefficients can be provided
- table containing temperature and corresponding parameter value of the material at the specified temperature

## Absorption Coefficient

# Fluids

## Density

- constant value at a reference temperature
- a polynomial function of temperature where a maximum of 8 coefficients can be provided

## Dynamic viscosity

- constant value at a reference temperature
- a polynomial function of temperature where a maximum of 8 coefficients can be provided

## Specific heat capacity

- constant value at a reference temperature
- a polynomial function of temperature where a maximum of 8 coefficients can be provided

## Thermal conductivity

- constant value at a reference temperature
- a polynomial function of temperature where a maximum of 8 coefficients can be provided

## Coefficient of thermal expansion

- constant value at a reference temperature
- a polynomial function of temperature where a maximum of 8 coefficients can be provided

## Thermal interface materials (TIM)

# How to input temperature-dependent material properties?

For fluids, it is possible to enter temperature-dependent values. The following input options are possible:

- A constant value at a reference temperature:

$\kappa = 100$ - A polynomial in function of temperature where a maximum of 8 coefficients can be provided:

$\kappa = [1,2,3,4,5,6,7,8]$

This array represents the coefficients of a polynomial:

$\kappa = 1+2T+3T^2+4T^3+5T^4+6T^5+7T^6+8T^7$ - A table containing the temperature and corresponding parameter value of the material at the specified temperature:

$\kappa = [[273,100],[283,100],[293,120],[303,120]]$

Note

It is not possible to insert temperature-dependent properties for solids or thermal interfaces, only for fluids.

Important

When creating a fluid, the input for all properties should be identical. This means that either all properties are constant, or tabulated or polynomial, mixing them is not accepted.

Updated 22 days ago