# Simulation Fluid-Structure Interaction 2D Water Wheel

In this simulation of a fluid-structure interaction a 2D water wheel is set in motion by a water jet. The water wheel (or water mill) is modeled as a rigid body and has only rotational degrees of freedom around the z-axis.

Figure 1: CAD groups created in NOGRID's COMPASS

Figure 2: Setup of the FSI 2D water wheel case

Figure 3: Result view of the FSI 2D water wheel case in NOGRID points' GUI

Figure 4: Animation of the 2D FSI water wheel

The fluid-rigid body interaction simulated in this study is solved fully coupled with the Lagrangian method. Fully coupled means that the motion (translation and rotation) of the water mill (= the rigid body) and the fluid variables for velocity and pressure are solved simultaneously in a large solution matrix (no iterative switching back and forth between the solution variables necessary). In engineering, this fluid-structure coupling (FSI Fluid-Structure-Interaction) refers to the consideration of the mutual influence of moving, not necessarily rigid bodies and a flow. The interaction between fluid flow and bodies occurs in many physical applications.
The water flow causes the rigid bodies to rotate due to the forces and torques exerted on the bodies by the fluid. Conversely, the movement of the water mill causes changes in the flow. If the flow also changes due to the structure, there is a so-called real, two-sided fluid-rigid-body coupling. If several rigid bodies are involved, the movement of one body can of course also be influenced by collisions with other bodies.

As with every rigid body in the FS coupling, the water mill, which is mounted around the z-axis, is assigned a weight and a mass moment of inertia. The rigid body thus behaves in accordance with the forces acting on it from the fluid. Conversely, of course, the flow is also influenced by the rigid bodies. The water mill is positioned here without any friction, i.e. it can turn without any force.

NOGRID points can be perfectly used for designing and problem solving for all kinds of FSI processes. NOGRID points helps to understand the flow by being able to calculate and visualize the mass, momentum and motion of single and multiple rigid bodies. You receive transient values ​​with which you can analyze and evaluate the efficiency of the components or processes.

NOGRID unites abilities to handle free surface flow and moving parts in the domain and allows the simulation of any conceivable geometry and operation modes such as

• computation is in full 3D solving complete Navier-Stokes-Equations
• easy and intuitive setup also for FSI (Fluid-Structure-Interaction) cases
• free definable material properties by equations or curves,
• evaluation of chemical reactions and corresponding heat source terms
• open or closed domains including inflow and outflow areas (non-batch mode)
• moving of parts

## Nogrid's strengths

NOGRID's particular strengths are the rapid preprocessing (no fluid grid needs to be generated, only the boundary mesh, inner finite points are generated automatically depending on User setting initially and during computation) and the outstandingly short computation time even for complicated cavities.
As you can see in the image below, the boundary of the geometry still requires a mesh to allow the interior finite points to detect the boundary. The boundary must therefore be meshed and the finite points inside are automatically generated during the simulation controlled by User specifications.

## What is CFD from NOGRID?

CFD solves the fundamental equations that define the fluid flow process. With CFD software from NOGRID every engineer makes better decisions by predicting, analyzing and controlling fluid flow, heat and mass transfer or chemical reaction. By using NOGRID software you receive information on essential flow characteristics as for example flow distribution. Using it additional to testing and experimentation NOGRID software helps to improve the evaluation of your design – resulting in better construction and operation parameters, increasing planning security and money savings due to faster time to the marketplace for your product or process.

## Choose NOGRID

With NOGRID, you choose professional CFD software and services – our aim is helping you to be successful. When you decide to work with NOGRID you choose close cooperation with a dynamic, flat hierarchies-organization. Short information channels result in quick and accurate professional support and service. Our team consists of highly qualified employees, who are experts in fields such as numerical simulation or computational fluid dynamics. Based on our know-how, we are pleased to offer the following services, responding to your individual requirements:

## TRAINING

In our two-days training courses you will learn, how to use NOGRID CFD software efficiently. Our technical support team will teach you how to handle and solve different cases.

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