Lecture

Turbulence: Near-Wall Treatment & Turbulence Models Guidelines

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In course

ME-474: Numerical flow simulation

This course provides practical experience in the numerical simulation of fluid flows. Numerical methods are presented in the framework of the finite volume method. A simple solver is developed with Matlab, and a commercial software is used for more complex ...

Description

This lecture covers the near-wall treatment in turbulent flow simulations, comparing wall function and near-wall model approaches. It also discusses guidelines for choosing turbulence models, variations, near-wall treatments, model parameters, and appropriate mesh. A case study on turbulent flow past a blunt flat plate is presented, highlighting the importance of model selection. The instructor emphasizes the complexity of turbulent flows, the hierarchy of simulation approaches, and the challenges in modeling turbulence. Validation of flow solutions is crucial for accuracy, and the lecture concludes with references for further study on turbulence and its modeling.

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Instructor

Edouard Boujo

Official source

Related concepts (3)

Turbulence

In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between those layers. Turbulence is commonly observed in everyday phenomena such as surf, fast flowing rivers, billowing storm clouds, or smoke from a chimney, and most fluid flows occurring in nature or created in engineering applications are turbulent.

Wake turbulence

Wake turbulence is a disturbance in the atmosphere that forms behind an aircraft as it passes through the air. It includes a variety of elements, the most significant of which are wingtip vortices and jetwash. Jetwash refers to the rapidly moving gases expelled from a jet engine; it is extremely turbulent but of short duration. Wingtip vortices, however, are much more stable and can remain in the air for up to three minutes after the passage of an aircraft. It is therefore not true turbulence in the aerodynamic sense, as true turbulence would be chaotic.

Fluid dynamics

In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation.