Flow Definition and 1000 Threads

I recently re-read an article by Muller (https://arxiv.org/pdf/1606.07975.pdf) about the flow of time, and the possibility of time reversal given sufficient energy dissipation (basically during black hole evaporation, he concludes). Although the paper is on arXiv and not peer reviewed, Muller...

Using a pump we are cycling water through a capsule with filter media inside; while measuring the flow rate (l/min) and the pressure (psi) going in and the pressure going out. The water is cycled back into the same storage tank. As the flow rate increases the differential pressure should change...

Hi, I have a question about air flow. My room is located on the corner-end of my building, on the 7th floor. I have two windows, each one facing a different side of the building, and one of the windows typically produces the breeze, and the other never does. When the door to my room is closed...

Hello PF, I am new to the science of turbulence and fluids but recently I have been working with my professor on 2D steady state turbulence and I was looking for a way to model and simulate this scenario: I have a flow affected by a spatially varying magnetic field and having a current pass by...

Homework Statement We bind two batteries with voltage 2V and 1.7V with inner resistance 0.2Ω and 0.1Ω in parallel series in such way that we bind each positive poles and negative poles together. What current runs trough the circle? What is the voltage between contact points of the batteries...

Homework Statement I don`t know if the image will show so I`m also adding a link to the image of the problem. This problem is a modification my professor made to the one in the link below(*), he changed the rigid diathermic partition into a movable partition. I`m supposed to find the...

Homework Statement A pump is used to move water through a pipe of diameter 150mm, Figure below. The water has a temperature of 20 Celsius and an absolute pressure of 100KPa. The pump moves the water up a vertical distance of 2m and the water exists at atmospheric pressure. Q1) Assuming the...

I am simulating flow through porous medium with VOF method and species transport. For phase change i have Lee Model, and i have no idea about the evaporation frequency and condensation frequency Second I am using the evaporation frequency as 30. The liquid is n-heptane while for vapour phase i...

Hi there, I am currently looking to build a rotating kiln to provide the necessary heat/res. time/gases to react a solid feedstock. The problem that I can envision, however, is that the solid (which is fed as small particles) may become entrained in the counter-current gas flow inside the...

I'm having a brain storm, If I have an 8 cylinder 4 stroke engine running at 4000 rpm over a 10 minute test and it consumes 4.4 Kg of fuel, then is the fuel mass flow rate as simple as the 4.4 Kg divided by the time to give me an answer on Kg/sec ? Thanks,

Looking for existing examples of or guidance on building computer simulations of simple N-bodies in relativist situations. Of particular interest is the simulation of a planet orbiting a star whilst that trivial solar system is caught in a dark flow of relativist velocity; maybe .8 or .9 C. Not...

So I'm working on a method to allow control of a drop at different speeds. An idea my team had was to sit our test object on top of a piston, and drop the object by allowing the piston/plunger to drain out of a port at the bottom. We can't seem to wrap our heads around how the size of the...

Greetings, I am trying to understand how to setup/solve for the pressure drop across an orifice L=3.5in The pipe diameter starts at 1in, then abruptly decreases to 0.5in for the length of the orifice, and abruptly transitions to 1in diameter. (See the attached file for an illustration.)...

Homework Statement At point A in the flow of a compressible fluid, the flow speed is 100 m s−1 and the Mach number of the flow is 0.6. Find (i) the maximum possible flow speed on the streamline through A, and (ii) the flow speed at a point where the pressure has fallen to half its value at...

Hi. There is a problem that I have been working on and I seem to be getting somewhat unrealistic results. Can anyone critique my modeling method? Problem: Heated air enters a duct of length L at temp T_h. The outside of the thin walled duct will have convection and radiation both being...

Greetings, I have very little experience with fluid dynamics and I was wondering how I can calculate a pressure drop across an abrupt change in diameter of the piping used for water. Any help is appreciated! Thanks!

Homework Statement Consider a layer of paint on a vertical wall, with uniform thickness T and a yield stress of Tau_0. (Paint is a Bingham Plastic). a) Derive an expression for the maximum thickness T0 that can be sustained without vertical flow.b) Derive an expression for the velocity profile...

I feel like this is easy to answer but I'm coming up with answers I don't trust. Basically, I have a tank of air where I want to keep the pressure at a certain value. Let's say 1 psig for the sake of argument. I have a 1/2" ID hose connecting to inlet flow to the tank and an outlet hose of 3/4"...

suppose a water falling from pipe that above the ground with 5 meters, what is the equation that describe the level of water ( h) from pipe the hole at every moment of time? consider the pipe hole is circle .

Einstein showed that the dustinction between past and future is an illusion using simultaneity, so, why do we experience a flow of time? Why is everything in the 'now' flowing toward the future, and not the past? Also, why do we all experience this flow the exact same way?

Reading the Wikipedia entry about the Navier–Stokes equation, and I don't understand this second term, the one with the outer product of the flow velocities. I mean, I understand the literal mathematical meaning, but I don't have an intuitive idea of what it physically represents. When I make...

When a car is parked and not running... is the radiator water (or coolant) pump totally shut that water from the radiator side can't enter the engine or in equilibrium (what's the exact term)? The water pump is a centrifugal pump.. does this totally shut the inlet and outlet from mixing so that...

Hi guys, I'm trying to delve into compressible flow and in the various textbooks I'm reading I've found two school of thoughts when it comes to how to calculate the threshold (or error compared to incompressible flow) of 'M' when to consider a flow compressible. In Fundamentals of Aerdnyamics...

I need to model a system of water flow from a gate whose opening is a function of time the height of the reservoir = H width of the gate = w opening of the gate = f(t) = 0.01t^2 how can i create a differential equation that takes an account of the varying area of the gate?

Hi guys, I am involved in some research on modelling sound from fluids through mirco annuli and i have been trying to get some of the basic fundamentals on generation of sounds from turbulent flow. Unfortunately most of the online literature do not give much details on the physics of such...

Hi, I am wondering how I may calculate the rate of water flow into a container(say, a empty box) with a hole in it, and with the whole box immersed in water. Does it have something to do with the force of water pushing against the container, and calculating how fast water can flow through the...

Hello I have a point that I don't understand. In open steady flow systems, we use SFEE, where there's a term W in addition to a term PV, which are different things. When we analyse a cycle like Rankine, we always consider either W or PV, but not both. I also think that W=PdV always. Why that...

I have a 5/8" tube that air is blown through. I want to subdivide the center section using .1" tubes so that the same volume of air can be blown through it. It will start as 5/8", but immediately be divided into the separate .1" tubes, then end as a single 5/8" tube. How many .1" tubes would I...

Hello everyone, I am currently working on an undergraduate club team for the Intercollegiate Rocket Engineering Competition. I am attempting to do a calculation to determine the pressure needed in a vessel leading to another pressurized combustion chamber to achieve a desired mass flow rate...

A building has a water inlet and outlet. The static water pressure at the buildings water intake is 5 bar. I'm trying to determine how much water this outlet will deliver when its valve is fully open. In that state, the pipe size and length will result in a certain head loss that I can calculate...

Homework Statement A 529 g piece of copper tubing is heated to 89.5°C and placed in an insulated vessel containing 159 g of water at 22.8°C. Assuming no loss of water and a heat capacity for the vessel of 10.0 J/°C, what is the final temperature of the system [c of copper = 0.387 J/g · K]...

Fluid comes in at ##T_1## and comes out at ##T_2## and I know that heat is exchanged with steam at constant ##T_{steam}##. If I want to know the Surface of the exchanger then ##US(T_{steam}-T_{fluid}) = \dot m_{fluid} cp_{fluid} (T_2-T_1)## My question is, since ##T_{fluid}## changes, which...

Hi pf, I have a reaction ## aA → bB ## in a PFR reactor. The simplest equation to write is: ## \frac {dF_A} {dV} = -R ## where ##F## is the Molar flow rate. ##F = C_A*Q## where ##Q## is the volumetric flow rate and ##C_A## is the molar concentration of A. My textbooks says that if ##a=b##...

Hello! When water flows through fittings like U bends, elbows, etc, is kinetic energy lost and velocity reduced?

I'm panicking right know, and I wonder if someone can answer these questions: 1) Nm^3 is a unit of measurement for Volume or Moles? 2) I have a flow at T=500K and, let's say, it is Q = 100 Nm^3/h When I find the value of the flow at T=500K I do ##Q_{real} = Q* \frac T {273.15K}##. The new Q...

Can laminar and turbulent flow be used to explain dripping blood? Be it blood dripping from a weapon/ impacting on an uneven surface?

Consider an underfloor heating system in an apartment building. Each apartment has its own distribution box with a number of loops and a thermostatic mixing valve set to 35°C. The loops are intended to work with a ΔT of 5°C (35-30), and the riser pipe supply temperature is 75°C. Say there are...

I have a RC circuit which also includes a battery, the capacitor has some charge initially before we put all the components in the circuit. Now as I connect all of them then charge will start to flow, but wheather this charge will be the sum of initial charge on the capacitor and the new charge...

Homework Statement Consider the surface, S, in the xyz-space with the parametric representation: S: (, ) = [cos() , sin() , ] −1/2 ≤ ≤ 1/2 0 ≤ ≤ os(). The surface is placed in a fluid with the...

I'm studying Newton Raphson Method in Load Flow Studies. Book has defined Jacobian Matrix and it's order as: N + Np - 1 N = Total Number of Buses Np = Number of P-Q Buses But in solved example they've used some other formula. I'm not sure if it's right. Shouldn't order be: N + Np - 1 N = 40 Np...

I know that under some conditions time runs slower or faster depending on the speed we have relative to an inertial frame of reference. However if I understand correctly for an observer that is moving with say 90%c though time runs much faster, for him the time runs in a normal way (I mean he...

Hi there, prob a simple question for you physics gurus, but this application is for a race car, and question relates to air flow velocity through a pipe, in particular exhaust and intake. Now, my thinking for the exhaust (push) is that by going from a small diameter to a large diameter will...

Homework Statement A 40cm well was drilled penetrating straight into unconfined aquifier at depth of 90m . The other wells were drilled at a distance of 20m and 100m from initial well have decrease in water level of 12m and 8m from groundwater level . If the aquifier has a permeability value...

I have this simple circuit I know that if a consider the wire from the + of the battery until the + extreme of the resistor, in this portion the wire has the same potential. The same thing regarding the portion of the wire beetween the - of the battery until the - of the resistor. If this...

We all think that electric current is the electrons flow without mass transfer in conductor, i.e. charged lepton flow. But charged baryons flow can also deemed as "electric" current, e.g. ionic current. My question is that charged baryons flow can induce magnetic field? Same amperes, then same B...

I am struggling to fully grasp the concept of flow work for a non-deformabable control volume. Nearly every source puts it in this way: flow work is the work required to push fluid into and out of the control volume and as such is defined as Pv on a unit mass basis. But how can this work be...

Most engine specifications I have found only provide the engine mass flow rate for take-off setting. For example, the V2500 has a mass flow rate of 354.25 kg/s. How does the flow rate vary through different power settings? For example, if the engine is on idle, will the mass flow rate be 0...

Hi everyone. Let me give a little bit of background on the problem I need help understanding. I want to plumb an aquarium that has a sump and move the water from the sump to the main aquarium using a pump and 1" PVC pipe. The total system pipe length is going to be roughly 10 feet total with...

Hi PF! I'm trying to model a fluid dynamics problem where there is flow in a wedge. Length scale is 160mm and two fluid phase: air sits on top of silicone oil. Boundary conditions can be to specify height conditions, flow rate, et cetera. Very low gravity, so surface tension is very relevant...

Does Pressure multiplied by volume multiplied by volumetric flow rate equal Force?