Questions tagged [turbulence]
The turbulence tag has no usage guidance.
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Characteristic scales in Thin Shear Layers Equations (Aerodynamics)
I am struggling to understand what characteristic scales mean in the context of thin shear layer equations. I am referring mostly to the following paragraph from the book "Turbulent Shear Layers ...
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What are the forces acting on a rectangular polymer film submerged in a turbulent flow (stirred tank)?
I am new to research in fluid mechanics and for one of my experiments, I'd like your help.
I need to write a force balance on a polymer film in a cylindrical tank at a fixed position.
The film moves ...
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Dimples on a golf ball, dimpling on the Mythbusters car, and the terminology used common to both
This post is strategic. I have an answer to the Mythbusters dimpled car question which was asked elsewhere on SE, but since I have a 1 reputation score at the moment and cannot post its answer, ...
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Why are Reynolds Stresses time-varying?
The time-averaging operator definition gives us
$$\overline{u_iu_j}=\lim_{T\rightarrow\infty}\frac{1}{T}\int_{0}^{T}u_i(x,t)u_j(x,t)dt.$$
From my understanding, this should mean that the Reynolds ...
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Why is the turbulent kinetic energy $k=\overline{v_1'^2}+\overline{v_2'^2}+\overline{v_3'^2}$ even in 2D cases?
I'm writing an essay which partly includes writing about the Reynolds stress model where the dissipation term $\varepsilon_{ij}$ is assumed to be isotropic (since dissipation mostly occurs at small ...
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Help with friction factors for non-Newtonian fluids
I've been researching about friction factors for non-Newtonian fluids and I've found quite inconsistent results. The power-law model correlations I've tested do not agree (within some interval) as to ...
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Imposing/ensuring a constant mass flow rate in turbulent flow simulation
I'm trying to simulate using Finite Elements (non commercial software) the Tube Bundle benchmark problem:
http://cfd.mace.manchester.ac.uk/ercoftac/doku.php?id=cases:case078&s[]=tube&s[]=...
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What is 'wavelength' with reference to turbuence?
When reading about turbulent flows and turbulence spectrum I frequently come across the terms 'wavelength' 'wavenumber'. I understand that the energy is transferred from larger eddies to smaller ones ...
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Does turbulent river flow classify as uniform?
I found this meme in a facebook group on engineering concepts:
I selected A (steady and uniform). In selecting A I assumed the width of the river to remain constant along its path and no parameters ...
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Ideal funnel design for powders
I'm designing a funnel/bottle for a powder. My goal is to have all of the bottle's powder contents come out when inverted. However, the powder has a tendency to stick to itself (like flour or brown ...
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Distribution of turbulent energy dissipation in a stirred tank
Is detailed experimental information on the distribution of energy dissipation in a stirred tank(45o Pitch blade) available? I require this variation in all directions in a standard stirred tank ...
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Von Karman mixing length $l=k \frac{du/dy}{d^2u/dy^2}$
In a fully developed turbulent flow of an in-compressible fluid inside a pipe of radius $R$, velocity at the center is $U_m$. If we define $U^*=\sqrt{\tau_0/\rho}$, where $\tau_0$ is the wall shear ...
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Turbulence model for low reynolds problem
I'm simulating the flow in a capillary with a sudden expansion. The small capillary has a diamater of 250 µm. The big capillar has a diamater of 1000 µm. My flow rate ist $ 1\frac{ml}{min} $. Using ...
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Why Taylor's microscale gives us information about the smallest scales of the flow?
So I understand the principles of two-point time correlations (covariance) and how you can just normalise that to get the autocorrelation. I also understand the integral time scale which is quite ...
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Direction of rotation of turbulent eddies in channel flow
Suppose we have a isotropic homogeneous turbulent channel flow. We know that this flow is associated with many swirling eddies of different length and time scales. I need to know the direction of ...
