# MULTIPHYSICS

# OPPORTUNITIES to combine your physical questions.

The world we live in has diverse impact on us. Mechanical forces, fluid forces, wind, heat, cold or electro-magnetism are just some examples for such physical phenomena. The effect of each of these can be individually simulated by FEM. However, Multiphysics describes the coupling of different disciplines in one analysis. Hereby the combination possibility only depends on the topic and is almost unlimited.

Most technical products have to work under changing thermal conditions. As some examples may be mentioned a motor beating up during running, a heat exchanger, a chiller or an industrial plant. Other examples are rooms which have to be heated or cooled or insulated gas tanks. All these applications undergo thermal changes in time or in their structure.

There are three main causes for the transport of thermal energy within the system:

- Conduction
- Radiation
- Convection

We apply Finite Element Method (FEM) and Computational Fluid Dynamics (CFD) simulations to analyze the temperature distribution within the structure or the surrounding fluid.

### Static-thermal simulation

For the static-thermal simulation, the temperature is defined as boundary condition at corresponding locations over the structure. Thus, the temperature distribution or the temperature field within the construction can be determined with little effort.

Use cases are among others:

- Insulation of a tank
- heat exchanger with a defined inlet and outlet temperature
- engine room, which is heated by units and cooled by fans
- circuits, controllers and sensors

### Dynamic- thermal simulation

In the dynamic-thermal simulation, the time-dependent change of the temperature within the structure is of interest. Thus, the warm-up or cooling in the time domain can be simulated.

Use cases are among others:

- heating up a tank
- cooling down a room
- heating a structure in fire (fire test)

Changing temperatures within a component lead to deformations. When constraints arise due to boundary conditions or temperature differences within the structure, stresses occur within the material. We combine the results of the thermal simulation with a mechanical Finite Element Analysis to determine these deformations and stresses.

These results can then be combined with other mechanical loads within the FEA. This is of great importance, for example, in industrial plants such as chillers, heat exchangers and boiler plants. These must withstand forces and pressures during operation despite varying thermal loads.

For dynamic thermal calculations, strength calculations can be performed on a sample basis. These then represent snapshots. Alternatively, the strength in the time domain can be transiently calculated and evaluated.

Usually, the material properties of the materials used depend on the temperature. In the case of metallic materials, a reduction of the modulus of elasticity and tensile strength leads to failure of the entire component in case of fire. In our FEM simulations we take this effect into account.

A special case of this area are fire tests. If these are carried out experimentally, the costs are significant, especially as the test body can no longer be used.

A more efficient solution may be to carry out the fire test by means of an FEM calculation. In this case, the temperature occurring due to the fire is applied to one side of the test body and the propagation of the temperature through the construction in the time domain is simulated. Thus, the suitability of the insulation for fire doors, ceiling panels or walls can be examined. The resulting deformation can also be determined. Thus, gaping joints of gaskets or screw fittings, through which flue gases can penetrate, can be found.

Another advantage of the FEM calculation compared to the experiment is that variations in the case of an insufficient result can be carried out very inexpensively. Also potential for optimizations can be easily recognized and analyzed.

We carry out fire tests for you according to common regulations such as the 2010 FTP code.

## We control complexity.

## REFERENCES

## A selection of our references:

- CFD calculation of fire spread on board of a cruizing ship (FIREPROOF project/EU)
- CFD calculation of fire fighting by a mist spray system (FIREPROOF project/EU)
- CFD calculation of the air ventilation inside an engine module and an air supplying moduleof a locomotive
- FE calculation of strength and thermodynamics of a 22,000 m³ FLNG-FLEX gas tanker
- Static and dynamic finite element calculatione of the stress and temperature distribution of a LPG tank
- Investigation of the dstrain within the insulation of an LNG Tank
- Model generation of an entire burning chamber and transient numerical calculation of a B15 fire test for a silicate ceiling
- Simulation of the fire test of an A30 door

## S.M.I.L.E. - FEM

## GmbH

Winkel 2

D-24226 Kiel / Heikendorf

fon: +49 431 - 210 80 20

fax: +49 431 - 210 80 28

e-mail: info@smile-fem.de