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Transition to Turbulence Series – Transition Scenarios

Motivation: There are various type of instabilities for a number of flow patterns. The intention of this post is to investigate how these instabilities may trigger laminar-turbulent transition. I shall do my best to classify these routes leading from a stable laminar to a disturbed one flow, and base my path on the mechanisms responsible …

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All About CFD – Mapping the Territory – Newsletter 1

My name is Tomer (Tom) Avraham. I have been around fluid dynamics, CFD and Physics in general for the past 20 years. Spent time at work places that I can nothing but own great gratitude for (Israeli Aerospace Industry, Elbit, As head of engineering in Ansys Channel Partner, as a consultant to STAR-CCM+ CP, continued …

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Nonmodal instability of PDE discretizations  – The Need For Linear Growth Mechanisms – Prolog

Turbulence is the name given to imperfectly understood class of chaotic solutions to the NSE in which many (and denied a spectral gap) degrees of freedom are excited (If we call a dog’s tail a leg than how many legs does a dog have?… It’s still four!) H. Aref 1999. This post serves as somewhat …

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Nonmodal instability of PDE discretizations – Spectra Analysis – An Introduction Primer for ByPass Transition

In this section we're going to pull out a few tools from our analysis arsenal and pay very close attention to what might seem at first like odd results. Doing that would be best on well known basic flows, i.e. Plane Poiseuille, and then Blasius boundary layer, pipe flow and coutte. Plane Poiseuille It is …

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Nonmodal instability of PDE discretizations – Transient growth through the mathematical standpoint – A mathematical primer to bypass transition – Part I

All cool, but let’s start with some simple and known algebra background of the modal eigenvalue kind:What exactly do eigenvalues offer that makes them useful for so many problems? We believe there are three principal answers to this question, more than one of which may be important in a particular application. Diagonalization and separation of …

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