A regime of nonlinear viscous flow characterized by random, rotational motion with a wide range of length scales. Its study is critical to many fields, such as aerospace, atmospheric science, chemical engineering, and astrophysics.

learn more… | top users | synonyms

4
votes
1answer
56 views

Is the flow of a viscous fluid in free space under no pressure gradient always laminar?

Consider a (Newtonian) incompressible viscous fluid in three spatial dimensions, whose velocity field $\mathbb{v}=\mathbb{v}(x,y,z,t)$ moves according to the Navier-Stokes equations $$\tag{1}\label{...
0
votes
1answer
46 views

Why does laminar flow turn turbulent(*) in external fluid flow and why doesn't a fully developed laminar flow turn turbulent in flow through pipes?

(*:with increase in distance from the leading edge.) I would appreciate if you give detailed explanation for the first question and then apply the same logic to answer the second.
-1
votes
0answers
15 views

Difference between turbulence and instability

One of the tasks of my current research is to study the instability of a viscoelastic fluid in a co-rotating cylindrical system. I have observed some patterns but cannot say if they are unstable or ...
1
vote
1answer
34 views

History of Turbulence suggestions

I am looking for extensive historical accounts of turbulence that ideally is strong in math and physics (at least giving references). Any suggestions? The only book I found is "A Voyage Through ...
0
votes
0answers
32 views

How is zonal flow defined and computed?

The transition to turbulence in pipe flow was recently observed to be in the same universality class as directed percolation. This was done by reinterpreting the turbulence and laminar flow in terms ...
0
votes
1answer
23 views

Spin on the rack

Bike mounted on hitch rack. Why wheels spin constantly while I drive? I can't find anything on the internet. The kids in the other cars love to watch them
4
votes
1answer
70 views

Why is turbulence caused?

In high Reynolds numbers we have turbulent flow. This is because the inertial forces are much greater than the viscous forces. I understand inertial forces to be actually the fictional forces due to ...
0
votes
1answer
33 views

Trouble understanding a formula in Turbulence

I'm very new to turbulence.I'm reading this book on "Turbulence: An introduction for scientist and Engineers" by Davidson. I came across this formula for energy dissipation. This is in chapter one. I ...
1
vote
0answers
29 views

Transverse and longitudinal random forces

I am trying to read following article: http://arxiv.org/pdf/1410.1262v1.pdf According to the equation (2.10) and (2.11), the random force is defined as $ \langle f_i(x) \ f_j(x) \rangle = \delta(t-t'...
0
votes
3answers
39 views

Wind restistance as function of temperature

Is temperature-dependent wind resistance the reason there's a significant increase in fuel consumption in my Prius car when air temperature drops by 30 degrees K from 300 degrees K? I think I see a ...
1
vote
0answers
44 views

Plane landing into a tunnel

Typical action movies cliché is landing a plane in a tunnel or even a flight in a tunnel. Let's drop any doubts about supreme heroic piloting skills of the characters etc. and focus on aerodynamics. ...
0
votes
1answer
14 views

Which are the best books I can refer for turbulent heat transfer and its computation?

I am a graduate student. I wanted to do computation on heat transfer problem mainly heat convection. I am working on turbulent regime. Can you kindly suggest some good books so that I can get ...
1
vote
1answer
60 views

Turbulence in gravitational waves

I want to understand physical meaning and possible implications of few terms often used in physics specially with regards to gravitational waves / space-time fabric Space-time fabric is disturbed by ...
3
votes
2answers
52 views

Is it possible that a plane in turbulences has more downward acceleration than gravity's

In multiple Hollywood movies and TV shows I've seen scenes where a plane enters turbulences and for a moment the people in the plane seem to move upwards relative to the plane. As far as I know, as ...
0
votes
2answers
63 views

Is it possible to let a flag ``stand frozen in time``?

It´s clear that a moving flag is a chaotic system. But is it nontheless possible, under certain conditions and a uniform wind velocity, to make the flag look frozen in time, i.e., flat without ...
1
vote
2answers
71 views

Misunderstanding about Reynolds number

I am confused about Reynolds number. I am trying to use the formula to see if NASCAR cars have laminar or turbulent flow. But I am not sure how exactly to use the equation in order to do such ...
0
votes
1answer
71 views

What is actually the characteristic length in fluid dynamics description?

In many fluid-dynamics models and quantities (Reynolds number, Strouhal number... generally various turbulent flow descriptions) there is a parameter (usually $L$ or $\ell$) descripted as ...
0
votes
1answer
54 views

Velocity of liquid molecules in turbulent flow

I was solving some questions when I came across this: what is the velocity of liquid molecules in contact with the walls of the tube? and the answer was given that it can have any velocity and then ...
1
vote
0answers
165 views

Numerical model for a Air core Vortex, why it's still so limited? [closed]

The Question can be Formally presented as follows; How is the Numerical Model (CFD, Navier Stokes) of fluid dynamics for Vortexes at in it's limits? At this Publication from 2013 at page 48 is said;...
4
votes
4answers
475 views

Does steady flow imply laminar?

Most secondary school textbooks, in their chapter about fluid dynamics, seem to suggest that "steady flow" and "laminar flow" are synonyms. Though I never received any fluid mechanics course when I ...
5
votes
1answer
150 views

Flow through a rifled pipe

In turbulent flow the friction is inertial for the most part: the chaotic flow causes the fluid in the faster moving center to interchange randomly with the fluid near the edge. This eventually allows ...
0
votes
1answer
52 views

Fluid flow around a cylinder

For an irrotational, incompressible fluid we can solve Laplace's equation for the velocity potential in a fluid in order to obtain the velocity field. This can be done for flow around a cylinder to ...
1
vote
0answers
78 views

The Optics of the Vortex (in Water): why there is a bright ring also in reversed flow?

This question is closely related to this one; The optics of vortex (in water): why there is a bright ring? In this case "physics girl" gives somehow an plausible explanation, and it's only debatable ...
60
votes
8answers
5k views

Turbulent spacetime from Einstein equation?

It is well known that the fluid equations (Euler equation, Navier-Stokes, ...), being non-linear, may have highly turbulent solutions. Of course, these solutions are non-analytical. The laminar flow ...
0
votes
0answers
29 views

Modeling Fluid Flow

I could really use some assistance. How would I go about trying to use Maple in order to model flow of a fluid through objects? For a rough example, such as entering an enterance of a maze and exiting ...
2
votes
1answer
109 views

Physical intuition on vortex sound generation

Whenever a fluid has a nonzero vorticity, it looses some of its energy in a form of sound wave. Formally is this mechanism described by Lighthill's equation or some related model (like e.g. Curle's ...
0
votes
1answer
49 views

How Does Rotational and Turbulent Motion Contribute to the Pressures of Dynamical Systems?

Rotational and turbulent motion can deepen a gravity well in a galaxy or galaxy cluster. In an analysis of the mass components of a large body, this would appear to be one of the components. Does it ...
1
vote
0answers
53 views

Dependence of the magneto-rotational instability (MRI) on thermal relaxation?

The MRI is the most efficient driver of turbulence in accretion discs (as measured by the effective scalar stress). The magnetic field, being properly coupled to the gas (weak coupling), connects the ...
5
votes
3answers
546 views

Why don't surfboards fly out the back of a utility truck when driving on the highway?

I have never had it happen myself and every time I throw my boards (shortboards not malibus) in the back of someone's ute, with no cover on the tray, they always assure me they'll be alright( the ...
1
vote
1answer
51 views

Why do you feel air moving past you when you walk?

I know that when you walk through the air you form a wake vortex and turbulent air behind and the vortex grows the faster you walk. When I walk past people I almost feel wind that's behind them. So ...
0
votes
1answer
77 views

How to model the mixing of two fluids?

In the context of a research project of mine, I am faced with the difficult task of modeling the mixing of two fluids in a container. I would like to achieve the following: Given a container (...
9
votes
1answer
134 views

How are the turbulent spectra determined in relativistic turbulence?

In a non-relativistic compressible fluid, the turbulent energy spectra are well-understood and appear to follow the Kolmogorov hypothesis. It would also appear that relativistic turbulence also ...
6
votes
2answers
114 views

What do the differences between spatial and temporal spectra imply about the structure of turbulence?

In the study of turbulence (theoretically, computationally and experimentally), we often appeal to Taylor's Hypothesis, which (very loosely) summarized means taking measurements at one point in space ...
0
votes
1answer
305 views

Turbulent and smooth flow of water from a tap

When water flows normally from a tap, we can say it is turbulent ( Pic 1 ). But when we attach a piece of cloth to the opening of tap, water flow becomes smooth ( Pic 2 ). We can say that by touching ...
1
vote
1answer
128 views

Velocity of water from tap to fill a cracked bucket to brim

Let us consider a real life situation. The bucket in figure below (drawn using MS PAINT) has an irregular crack of essentially small area. And I decide to open a tap above it and start filling it ...
0
votes
0answers
21 views

Limitation of Rytov approximation for turbulence

I have been working through the textbook "Laser Beam Propagation through Random Media" by Andrews and Phillips and have arrived at an interesting dilemma. For a second-order perturbation in the Born ...
3
votes
2answers
156 views

Why is the Reynolds number “the way it is?” Why is its order the way it is?

Why is the Reynolds number “the way it is?” Why is its order the way it is? I'm not sure if this is an appropriate question for this context, but I would like more intuition on this matter and so I'...
3
votes
3answers
994 views

Laminar vs Turbulent flow separataion

(Left is a laminar separation, Right is a turbulent separation) I have been having a bit of trouble understanding this concept. How come the laminar separation involves a much larger wake than the ...
0
votes
0answers
47 views

Any applications of kinetic physics on cosmological scales?

On galaxy cluster scales, one is usually forced to use approximate theories such as hydrodynamics or magnetohydrodynamics for modelling cosmological phenomena. I wanted to ask if kinetic theory is ...
1
vote
1answer
59 views

Reynolds Average Navier Stokes equations and turbulence scale

To obtain the time average of an unsteady term like $\frac{\partial u_{i}}{\partial t}$ by definition we perform the following: \begin{align} \overline{\frac{\partial u_{i}}{\partial t}} &= \...
2
votes
1answer
211 views

What is the cause for turbulence?

The transition from laminar flow to turbulent flow is usually told interms of Reynolds numbers. The Reynolds number is $Re=UL/\nu$ where $U$ is the speed, $L$ is dimensional length and $\nu$ is the ...
4
votes
3answers
176 views

Why are vehicles not pitted like golf balls?

I have read that non-laminar flow reduces drag on blunt bodies. Given that, why is pitting not used on motor vehicles?
9
votes
2answers
442 views

The optics of vortex (in water): why there is a bright ring?

This picture is from this YouTube video from "Physics Girl", which shows how you can generate vortices in a swimming pool by using a plate: And there she explains the creation of the shaded circle ...
1
vote
1answer
231 views

Can a vacuum make a turbulent flow laminar?

When a vacuum is generated next to a turbulence, does the flow towards the vacuum become laminar? Imagine a vacuum cleaner tube is put next to turbulent air movement, does the "suction" change the ...
2
votes
0answers
42 views

$L^p$-weighted enstrophy calculations

Mathematician here, only somewhat familiar with physics, but finding myself involved in a research project on fluid dynamics. I'm studying a 3D simulation of turbulent fluid flow, and we are currently ...
0
votes
1answer
318 views

What are premultiplied energy spectra?

When speaking about turbulence in fluid mechanics many times authors speak about "premultiplied energy spectra" but they never explain what really it is. I have searched for a definition but I did not ...
-2
votes
2answers
102 views

Turbulence and art [closed]

I read about turbulence a few days back.I saw a video showing the physics behind van gogh's starry night and physics.But I could not really understand the link between starry night and physics of ...
0
votes
1answer
39 views

Reference for passive scalar

I would like to learn about turbulence of a scalar advected by a random velocity field. I know that this problem can be solved analytically and that the statistics of the scalar field are intermittent....
1
vote
0answers
15 views

Why hydrodynamic turbulence without heat terms matters?

A lot of research is made on turbulence in "pure" Navier-Stokes equations (NSE). There is a notion of energy cascade when energy comes from larger scales to lower scales and than dissipate. However ...
0
votes
1answer
34 views

Influence of a defect on the flow field

I have a long microchannel where flows some water. The reynolds number is much smaller than one. Within the structure of this microchannel there is a big defect. It looks like a bump of size ...