Flow Definition and 1000 Threads

I hope you guys don't mind a bizarre question from a novice. I've learned just enough about fluid dynamics to be dangerous. Assume that we have a straight, rigid tube with a constant inner diameter. It's not long, let's say it's around a foot (in case that matters). We cut a chunk out of the...

Hi, I just had a quick question about conventions in potential flow theory: Question: What is the convention for ## \Gamma ## for the streamline ## \Psi = \frac{\Gamma}{2\pi} ln(\frac{r}{a} ) ## and how can we interpret the Kutta-Jukowski Theorem ## Lift = - \rho U \Gamma ##? Approach: For the...

Dear Everyone： Q： Please help me to understand why the torque of external load to the centroid is different from the torque of internal shear flow to the centroid in the asymmetric beam? Attached please refer to the following link for more details. Question version Original version Thank you...

I recently came across a Diaphragm flow switch whose operation many engineers are not familiar with. First. Supposedly in a normal pressure switch. The pressure will be a maximum when there's no flow, precisely because at zero flow there is no pressure drop anywhere in the system, so the...

I have two charged spheres connected to different ends of an infinitely long conductor. The first sphere has positive charge, another sphere has negative charge. Suppose that the electric field of the first sphere at point A is zero, and the electric field of the second sphere is zero at point...

hi guys I'm really struggling to get the expression for average speed in turbulent flow The book explains absolutely nothing about how the integration is carried out, in addition to the fact that the logarithmic term becomes undefined when r = R what I did was carry out the integration up to...

In this question, the particles are constantly transmitting their momentum to the rocket. The force required to keep the rocket stable can be express as ##\vec F=(\vec v-\vec u)\dot m##. However, when I tried to solve this question using the Newton's 2nd law, I found that the infinitesimal...

So, I actually do not know, if the formula given applies to this problem or not, so I wanted to check

Hi, I was thinking about principal stresses and unfortunately this is a bit of a dark spot for me in my education. I understand principal stresses as the stresses that are present when the co-ordinate system is oriented such that there are no shear stresses, and only normal stresses. As such...

Working out as follows x= (20-6)/20 = 0.7 Fk = k / air specific heat ratio Fk = 1.31/1.4 Fk = 0.94 xT = Fk * x 0.94 x 0.7 = 0.658 because xT < x = 0.658<0.7 flow through the valve is choked Expansion factor Y Y = 1 - x/( 3 x Fk x xT ) Y= 1- 0.7/( 3 x 0.94 x 0.658) Y = 0.623...

I have few conceptual doubts in fluid mechanics. Here is the one I will ask first. I want to understand the force direction acting on the solid liq interface during fluid flow, Let's say a fluid is flowing in a pipe. Now the fluid applies a shear stress at the walls of pipe in the direction of...

Hello everyone. I am newbie at MD. I started with Poiseuille flow. I try to model 3D Poiseuille flow of Argon gas confined between two parallel Platinum plates by using LAMMPS. I have one reference paper, as given in [1] below. I built my Platinum structure correctly and I placed Ar atoms and...

The Blackbird wind powered car travels directly downwind faster than the wind speed powering it. Typically a 10 mph wind from directly behind it will cause it to travel at about 30mph. I am trying to analyse how the car accelerates from rest. I know how it travels faster than the wind speed so...

Hi. I am currently doing my internship in the oil and gas industry (contractor) as process engineer. My supervisor give me a task to do some reverse engineering where i need to study how a spreadsheet (calculation) construct by other process engineer was been constructed. Ok the situation is the...

I have a problem. The task is to develop an differential equation of the airflow of a balloon. I know that it is dependent on the volume and pressure. But I can't get a good differential equasion. Can someone help me? [Thread moved from the technical forums, so no Homework Help Template is shown]

Pressure gradient normal to the local flow direction balance the centrifugal force associated with the curvature of flow.. Which centrifugal force inertial or "reactive" centrifugal force?

Electric currents and the things within are generally explained through the help of intuitive water current examples, where potential difference is explained through the pressure difference and electric current is explained as the flow of water. But I like to think in terms of some driving force...

Hello guys, I am looking to control the flowrate of water through a Solenoid Valve in a continuous closed-loop process. I inquired about Proportional Flow Solenoid Valves and these are a little too expensive and only a handful of manufacturers are supplying those. But I looked online for some...

Hi, I am trying to calculate how much water can flow with just gravity from water tank A to water tank B. Each tank as a 2" orifice on the side wall at the bottom. If water tank A is 100% full and water tank B is completely empty, if someone opens a 2" ball valve at the bottom of tank A, how...

Hi guys, I am confused about the heat transfer mode of between two contacting material, especially in a channel flow. Obviously, conduction or convection dominate the heat transfer process in the process with low object temperature . But I am not sure if I have a fluid of 500 Kelvin, flowing...

Good evening everybody. I am new here I hope it is okay to ask this question here. As part of a project I am trying to examine the effect of a pulsating laminar duct flow on the heat transfer behavior for constant heat flux at the wall for a Newtonian incompressible fluid. As such I am...

My first post here! I have calculated everything i need, except the thickness of the second layer dZ*, therefore i can't solve V3/V2=(R2ˇ2)/(R3ˇ2) Trying for days now, i would appreciate any help.

This is a past exam Q, I don't have the attached pressure enthalpy diagram. Q = 120kW Cp = Refrigerant enthalpy = I've looked this up, for ammonia enthalpy = 35.06 kJ / mol T2 = 5 degrees C = (5 deg C) (1100 kPa/300 kPa) = 18.33 deg C +273.15 K = 291.48 K T1 = 2 degrees C = (2 deg C)(1100...

I tried to created it but i dknt know how to even start

I need help solving this please. Its a past exam paper. requires wort to undergo 5% by mass evaporation in one hour does this mean starting vol is 500hl and after one hour vol should be 475hl Wort volume = 500 hl = 50,000 L / hr 1 L = 10^-3 m^3 50,000 L = 50 m^3 /hr = 0.833 m^3 / min = 0.01388...

Hi, I am trying to figure out the strength of the various type of airflow for my Venturi ejector device. Please refer to my diagram that illustrates scenario A or scenario B. The SAME amount of compressed air is injected for both scenario A and B. For simplicity, I have added to an electrical...

Suppose you have a cylindrical column filled with packed, irregularly shaped particles. The bottom of the cylinder is flat and closed except for an array of small circular holes, regularly spaced except for a ring around the edge of the bottom where there are no holes. So, holes everywhere on...

Flow coefficient in valves doesn't have any units. why?

I am working on a project where I have to calculate various results relating to the motion of a water bottle rocket being launched. I am currently stuck on trying to find how long the thrust period of the rocket is. The model for the rocket is as follows: It is a 2L (0.002m3 bottle filled with...

Hello kind people of PF I am looking to mount a fan on one end of a pipe but I'm not sure how much air can the pipe transfer. (Volumetric flow rate) The pipe is vertical and 15 meters long.It has a diameter of 10 cm. I'm looking to push air from top to bottom using a fan. Need to know the...

Maybe not the right sub-forum? I have a form to complete in which 2 sentences need to be converted into a flow chart of action which I think I understand but maybe I don't and would appreciate your consideration. Please consider the following scanned passage starting at Spousal Consent, It...

For compressible flow in a duct, mass conservation combined with reversibility (no entropy change) implies $$(1-\frac{u^2}{c^2})\frac{du}{u} = -\frac{dA}{A}$$ where u is the flow velocity of the gas, c is the speed of sound in the gas, and A is the area of the duct. I am assuming a calorically...

Mathematical proofs that many turbulent flows can be predicted at least in a stochastic sense. Under the right conditions, it turns out that the flow lines and vortices pretty much follow a fractal law. Popular version...

I know how to derive the formula, but I have no idea how to actually use this. Where it says ##50~cm## wide, I'm not sure if that's in the x-direction or the z-direction. ##W##, the width in the equation, is in the z-direction. ##\mu## can be calculated, but I'm not sure what the pressure...

I am trying to determine the flow of mechanical power through a structure like a drive shaft or even a simple lever. The components of the Cauchy stress tensor, ##\sigma_{ij}##, have units of force/area, so if I multiply by the velocity, then ##\sigma_{ij} v_j## would have units of power/area...

Hi there! I have recently been given this question by my teacher as shown below I'm struggling to see the set up arrangement for this circuit This is what I have drawn so far How would I fit in the third wire here and ensure I have closed loop circuit so that current can begin to flow...

I couldn't find any threads about this experiment on this forum, so here I try to introduce it and also I later have som suggestion to improve it. Very shortly the machine produce a ring formed sheet along a rod, which climbs up and at the end of the rod it stretch out and compress to a thin...

Basically the air pump on the left turns on and when it does, the balloon on the right fills up but the other does not. I also tried putting the pump upright but the left one just doesn’t seem to fill? Any ideas of why? There’s no air leak or blockage or anything

What will be mass flow rate of dry saturated steam through holes on a pipe. Pipe ID: 25mm, Steam Pressure 3 kg/cm^2, Holes' Dia: 3mm, Number of Holes: 5.

I'm studying fluid and propulsion mechanics by myself. I stumbled upon this website from MIT: http://web.mit.edu/16.unified/www/SPRING/propulsion/UnifiedPropulsion2/UnifiedPropulsion2.htm#fallingblock It states that "Newton’s second law for a control volume of fixed mass" is $$\sum...

Hi, I am trying to find out Force on a rigid body when it is completely inside a fluid with density p, i.e. the body is completely drowned in the liquid and then another liquid is pushed into the container with different density 'r' (such than r > p). Thanks.

Im trying to do some past exam papers. If i can get help with the method on how to solve and have correct formulas, it will help me. I) There is one formula in the notes to get mass flow rate: Heat lost by steam = Heat taken up by water GsHfg = (GwCpw)(change in temp) Gs x 2748 x 10x103 =...

Hello everyone, I want to ask something. Can we design a tube that can completely resist the flow of a fluid? Maybe using either viscosity or surface tension approach? Thanks

Here is the Q below I want to see if my values for part b) is okay? This is what I have tried: Any help would be nice! Thanks

I have two Gases where i know the molar flow rate of each gas. Is there any way to calculate the molar flow rate of the two gases together or is it just the average of the two molar flow rates?

how can i convert mass flow rate into molar flow rate using density of the gas.

Hello! I have a volume of 50 liters which I pressurize with air so that I read 1 bar on the manometer. But there is a leakage in the volume so after 30 sec the manometer shows 0,5 bar. What is then the air flow ( liter / min) of the leakage?

What is the difference between streamlined and steady flow? Is unsteady streamlined flow possible? If yes, could you please explain what are the characteristics of unsteady streamlined flow?

Hi all 😁 Hopefully it's ok to ask this question here. Ok so my project is a little bit redneck as opposed to being engineered science. I have been experimenting with burning waste oil in my oil furnace in my garage. It is an average house oil furnace with Beckett burner. ( burner has electric...

Pardon if the answers to my questions are obvious, because as usual I am trying to decipher everything on my own (as the material has not been taught to us quite well; then again it's graduate school). I just need someone to reassure me that I am understanding this correctly. Say for example I...