The motion of fluids (gases, liquids and granular material).

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42 views

To write work capacity of heart by symbols?

I know that the work capacity of the heart is Work capacity of the heart = pumping capacity x aortic impedance. I would mark work by W and impedance by Z. ...
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2answers
239 views

Equilibrium of of water level in punctured bucket?

Would a bucket with a hole in the bottom being filled at different rates with water come to to different equilibrium levels with in the bucket? Or would at any fill rate above initial flow rate of ...
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0answers
145 views

Shape of the “flow head” in Laminar flow in pipe

Laminar flow is a streamlined steady flow with a uniform gradient of velocity across the diameter of the pipe. I am familiar with the elementary treatment of laminar flow, like basic velocity ...
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0answers
72 views

Finding the appropriate source term for 2D Pressure Driven Flow in a Square Channel

I'm trying to solve the equation: $$ \frac{\partial^2 v_z(x,y)}{\partial x^2} + \frac{\partial^2 v_z(x,y)}{\partial y^2} = \frac{\Delta P}{\mu \Delta X} $$ This flow is supposed to be flowing in a ...
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1answer
126 views

Slope of a channel

I have a trapezoidal channel like this: The question is to get the slope of the channel such that we have a Chézy coefficient of 64 $m^{1/2}/s$. Given: $B= 76\: \mathrm{m}$, $y = 10\: ...
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1answer
83 views

Laminar flow in low-permeability material. Which is faster, gas or a liquid?

I consider a simple low-permeability material $(k \sim 10^{-18}\;\text{m}^2)$. Now I either apply a gas (e.g. nitrogen) pressure or liquid (water) pressure of - let's say $10\;\text{MPa}$ - on one ...
2
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1answer
88 views

Non-determinitric flow of water stream on vertical porcelain surface

I noticed several times while washing my hands that accumulated water when starts streaming vertically does not flow vertically in straight line on vertical porcelain surface under the force of ...
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2answers
7k views

Does pressure drop across pipe affect flow rate?

Let's say there is a main pipe containing $100\: \mathrm{m^3/hr}$ a fluid of density $750\: \mathrm{kg/m^3}$ and it's gonna be branched into 2 pipes (Pipe A and Pipe B) of the same diameter. If Pipe A ...
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0answers
121 views

Formula for residence time/turnover rate with unsteady state

I'm not sure this is the correct place to ask my question... but maybe someone could still help me. I'm looking for a way to calculate the residence time/turnover rate. I have the production and ...
2
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1answer
86 views

Whirlwind/tornado/dust devil in the middle of nowhere

I live in area which have many properties similar to desert. Many times when I drive by I see a whirlwind/tornado/dust devil of sand or other garbage parts. I would like to ask how this was normally ...
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0answers
92 views

How can I model computationally or experimentally the flow in my aquarium tank?

I have a 60-gallon aquarium tank and I have always wondered about the flow of water in the tank. Let's represent the flow of water in terms of a direction field representing velocity, so if we see the ...
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1answer
85 views

Fluid Virtual Mass

In this paper of Lighthill, the author studies the motion of a fish in a constant flow field $U$, modelling the movement of the fish as a deforming, rotationally symmetric, rigid surface in an ...
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1answer
147 views

What is the apparent viscosity in shear thinning turbulent flow through a pipe? [duplicate]

The explanation of shear rate in laminar flow is straightforward: We imagine small layers of fluid that glide on each other. Now, in turbulent flow, this does not work as there are no layers. If I ...
2
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2answers
183 views

The criteria for potential flow theory

I am learning aerodynamics. In this course a potential flow is denoted that a flow in which the rotation is zero everywhere. But the book told me that we can add vortex into a flow field, and we can ...
4
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1answer
948 views

What's the shear rate in a turbulent flow?

The explanation of shear rate in laminar flow is straightforward: We imagine small layers of fluid that glide on each other. Now, in turbulent flow, this does not work as there are no layers. I'm not ...
2
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3answers
504 views

Steady isothermal flow of an ideal gas

So I have a steady isothermal flow of an ideal gas through a smooth duct (no frictional losses) and need to compute the mass flow rate (per unit area) as a function of pressures at any two different ...
4
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1answer
199 views

Velocity of a viscous fluid through a tube

When a viscous liquid flows through a tube in a laminar flow, why is its velocity highest at the center? I understand the concept of shear viscosity and why the liquid in contact with moving plate ...
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0answers
115 views

Time required to fill a pipe line

This is quite embarrassing to ask, but I haven't done a fluid flow calculation in a very long time and when you don't use it, you lose it! I have a natural gas pipeline that I want to purge of air ...
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1answer
3k views

Flow Rate and Orifice Diameter

I have a electrical/electronics background and have limited knowledge of Fluid Mechanics. So, i will try to be as clear as possible. I am currently working with brake fluid in an ABS system and to ...
2
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0answers
152 views

Modeling Syringes e.g. with the ideal gas law

Gentlemen I have a similar yet very practical problem that might provide further insight. I'm trying to model a moving plunger in a syringe (something like a piston in a cylinder). At time zero the ...
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1answer
128 views

Does the termination point(level) influence water flow from a pipe

I get water to my home from a nearby Tank A at a certain height above ground level. I have a 1" pipe through which I get this water to my home.. I leave this water into my well by connecting a 1" tube ...
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0answers
102 views

Collision of two deformable bodies - limitation of work-energy theorem

I am attempting to model the impact of a deformable body (clean, dry sand characterized as a continuous fluid) with flexible diaphragm (in this case a sheet of rubber). Assuming that this is a closed ...
2
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0answers
63 views

Contraction and expansion after constricting flow though a pipe

If an orifice is placed inside a pipe with a smaller diameter than the rest of the pipe, fluid will follow a curved path in order to enter the orifice, and then expand. I was wondering at what ...
2
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1answer
58 views

Is there a name for a quantity that represents (volumetric) flow per unit of mass?

In a lot of medical literature about blood flow in the brain, researchers denote the amount of volumetric blood flow that passes through a certain amount of brain tissue as "cerebral blood flow". ...
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3answers
3k views

What about negative Pressure?

Here is something I see : Let's say the ideal fluid(water here) of density $\rho$ is drawn from a source by a motor and thrown upwards with a velocity $v$. Now we take the power of motor be ...
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2answers
3k views

what is the density of natural gas at 293K and 700 kPa? [closed]

I am trying to calculate the density of natural gas to define the amount of natural gas flow through an orifice. I am coming up with 5.45 kg/m3 Is this correct?
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2answers
275 views

Water draining from a height into the bottom of a reservoir

If I hang one 5 gal. Bucket directly above another, put a hole in the bottom of the upper bucket with a tube inserted just inside hanging all the way to the bottom of the lower bucket and fill the ...
6
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2answers
2k views

What does the Reynolds Number of a flow represent physically?

What does the Reynolds Number of a flow represent physically? I am having trouble understanding the meaning and the utility of the Reynolds number for a certain flow, could someone please tell me how ...
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1answer
116 views

Computational Fluid Dynamics methods

I have read some articles about the finite difference method on a cartesian orthogonal grid. I understand how it works when Dirichlet boundary conditions are used, or when Neumann boundary conditions ...
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1answer
149 views

Negative temperature and Absolute hot

This video explains that heat at negative temperatures flows from the negative object to the normal object. If the temperature of the normal object is absolute hot, what happens with the heat? The ...
2
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1answer
157 views

Application of plasma actuators for flow control of moving objects

I've recently been to a converence on plasma physics were, to my surprise, a lot of presentations were concerned with plasma actuator. Could someone, preferably in the field, tell me how long people ...
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3answers
1k views

When is a flow vortex free?

To solve problems in fluid dynamics one states often the assumption that the flow is vortex free i.e. $rot(u) = 0$ It is a basic assumption which is needed for potential flow problems etc.. My ...
2
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1answer
246 views

Experimental measurement of volumetric flow rate

The other day I with my team had to measure the volumetric flow rate through a pipe only using a 2000 mm$^3$ volumetric flask and a chronometer. The end of the pipe discharged to the atmosphere. As we ...
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2answers
853 views

Physics behind the flow of gas coming out of a balloon

I'm working with stratospheric balloons (latex ones) and I want to put a valve on it so it can float for a longer time. I'm trying to define which valve I should use, which demands I estimate the flow ...
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1answer
173 views

What is the term for heat generation by a flowing fluid?

I would like to know more about the heat distribution over time in a flowing liquid. To this end, I consider the Navier-Stokes equation (where the coefficients may be temperature dependent) and the ...
0
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1answer
737 views

Real world usage; pump flow vs pressure vs pump head, what is more useful in this situation?

I am currently making a water cooling system for my computer and decided to see if I could get some better help here than what people think they know on the computer forums. So for my cooling system ...
3
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1answer
1k views

how to determine if a vortex is laminar or turbulent

In a cylindrical chamber with a high diameter-to-height ratio; a fluid is tangentially injected. there is an axial exit to the cylinder. how do I determine if the vortex so formed is laminar or ...
4
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3answers
2k views

How is possible for current to flow so fast when charge flows so slow?

How is possible for current to flow so fast when charge flows so slow? We know electrons travel very slowly while charge travels at ~the speed of light.
4
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1answer
353 views

Compressible fluid flow through a branched pipe junctions

Backdrop: Designing a dust extraction system (LEV) with a branched junction. What principles allow for the calculation of volume flow rate and pressure at the inlets if the volume flow rate and ...
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0answers
69 views

Experimental data for gas flow through pipelines

Maybe some of you could point a good source of experimental data of gas flow through pipelines? What I need is a very simple flow of some gases through some diameter simple linear pipeline. A graph of ...
6
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1answer
308 views

Why do air bubbles stick to the side of plastic tubing?

I'm watching water with air bubbles flow through transparent plastic tubing. The inner diameter is a few mm. Bubbles typically are the same diameter as the tubing, with length about the same or up ...
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2answers
94 views

How would I work this continuity problem?

I am trying to design a system for a project and I need some input on if this is right or not. I have $10 \frac{kg}{s}$ of fluid flowing through a pipe. It breaks up into $10$ 1 inch diameter pipes. ...
3
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0answers
138 views

SU(2) critical point and volume dependence

I am doing multi-dimensional plots of $\beta_j$ for SU(2) for infinite volume to understand the flow behavior and I was wondering, before I go too much further, if anyone knew off the top of their ...
2
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3answers
916 views

Riddle: can you swim faster upstream than downstream (with respect to the water)?

A friend of mine posed a riddle to me: A man swims upstream in a river, which is flowing at an unknown rate. He is wearing swimming goggles. At a certain point he loses his goggles. 10 minutes later ...
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1answer
362 views

Hamiltonian Flow Map

I'm reading this article and am struggling with some of the terminology. What is the flow map for a Hamiltonian system? I'm looking for a rigorous definition really! Many thanks in advance.
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1answer
401 views

What is the particle residence time for given flow rates of gas mixture components?

For two different chemical substances there are two open valves with flow rates $$Q_1=a\frac{m^3}{h}\ \text{ and }\ \ Q_2=b\frac{m^3}{h},$$ leading into seperate cables. Next, the cables join, the ...
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0answers
201 views

Reduction in velocity in pipe

I have two pipes divided from main pipe. If I add one more pipe, what would be the amount of velocity in each pipes. I know the velocity of main pipe, then diameter and radius of each pipe. Edit: 1) ...
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4answers
601 views

Zigzag flow of water along a vertical glass window

I've observed this behavior many times. When it rains, the rainwater will form vertical channels along a glass window. The flow of water is mostly confined within these vertical channels and the ...
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2answers
6k views

Flow of liquid among branches

If water is flowing through big pipe is branched into 4 branches of small pipe. Lets say the flow is around 4 m/sec. I have the following questions: What will be the flow rate in each of the ...
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5answers
7k views

Will adding heat to a material increase or decrease entropy?

Does adding heat to a material, thereby increasing electrical resistance in the material increase or decrease entropy? Follow up questions: Is there a situation were Heat flux ie. thermal flux, ...