Fluid Mechanics

How it works

How it works

Fluid mechanical analysis with CFD (Computational Fluid Dynamics) serves the purpose of simulating the behavior of liquid and gas flows. The result is a variety of physical quantities, such as pressure, flow velocities and temperatures, to name but a few.

As it is with MBD and FEA, also for CFD 3D CAD geometry is required as input. The amount of details depend on the task. Fundamentally, meshes for CFD demand high quality and resolution, which is why they generally consist of significantly more cells than FEA meshes. After meshing, the boundary conditions are defined and the simulation model is solved.

Solution times for CFD models are the longest compared to System Simulation, MBD and FEA. The reason for this is often a transient simulation with small time steps, large meshes with many cells and, depending on physics, a much higher number of equations that have to be solved for each finite volume cell. However, CFD scales very well with the number of processors and we have access to appropriate resources.

Sometimes CFD simulations are the only way to get an accurate picture of a flow because measurements are difficult or even impossible.

Our Simulation Capabilities

Steady State and Transient Simulation

Steady-state analysis are usually less complex than transient ones, but due to physics they are not always possible or correct. Depending on the objectives of investigation, transient analysis are also often mandatory, e.g. in an in-cylinder simulation of an internal combustion engine.

Compressible and Incompressible Media

Calculation of liquids and gases, also at high speeds and pressures. There is a variety of tools on the market which can also simulate dense particle flows (DEM – Discrete Element Method), we don´t offer this option at the moment.

Single- and Multiphase Flow

Calculation of solid, liquid and gaseous phases, especially mixture preparation of internal combustion engines. For specific process engineering simulations, e.g. complex chemical reactions in a reactor, we have a strong partner network of specialists thanks to our longstanding contacts. Don´t hesitate to discuss your requirements with us.

Laminar and Turbulent Flow

ANSYS CFX® and Fluent® offer a wide variety of turbulence models which cover nearly every application.

Heat Conduction, Radiation and Convection

Calculation of conjugate heat transfer (CHT) between solids and fluids. Determination of temperatures and mapping onto structure for stress calculation.

1- and 2-Way Fluid Structure Interaction (FSI)

If the fluid pressure is not sufficient to deform the structure in order to change the flow domain, a 1-way coupling is sufficient. For example, pressure in a heat exchanger and subsequent stress calculation.

If the fluid pressure is high enough or the structure is so flexible that the flow domain changes as a result, a 2-way coupling must be carried out. For example, vibrations of a membrane in a fluid.

Co-Simulation with System Simulation

Possible, but not the preferred way due to the very different System Simulation / CFD calculation times. If possible, we recommend a CFD simulation and subsequent import of a simplified behavior model into the system simulation using FMI (Functional Mockup Interface). However, this kind of simulation is often done at internal combustion engines with charge cycle calculation and in-cylinder CFD simulation, which requires powerful compute ressources accordingly.

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