What is Steady flow: Definition and 27 Discussions

In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation.
Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fluid dynamics problem typically involves the calculation of various properties of the fluid, such as flow velocity, pressure, density, and temperature, as functions of space and time.
Before the twentieth century, hydrodynamics was synonymous with fluid dynamics. This is still reflected in names of some fluid dynamics topics, like magnetohydrodynamics and hydrodynamic stability, both of which can also be applied to gases.

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  1. B

    Engineering Steady flow energy equation in Thermodynamics

    I am looking for help on the following: a) Given the system shown in the figure below, derive the steady flow energy equation from first principle. b) Again using first principles, show how the energy equation would change for the case when the system is unsteady. I am trying to learn this...
  2. Kaushik

    B Uncovering the Complexities of Streamlined and Steady Flow in Fluid Dynamics

    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?
  3. F

    I Why in the steady flow of a fluid, the fluid cannot move through the wall....?

    Because of temperature, molecules of fluid have chaos movements.So I do not understand why in steady flow,the molecules of fluid can not move through the wall of flow tube?I think two layers of fluid exchange molecules while they move.How do we understand when saying: fluid can not move through...
  4. Perodamh

    Steady Flow, Thermodynamics First Law

    Homework Statement 12kg of a fluid per minute goes through a reversible steady flow process. The properties of fluid at the inlet are p1 = 1.4bar, ρ1 = 25kg/m3, C1= 120m/s and u1= 920kJ/kg and at the exit are p2= 5.6bar, ρ 2= 5 kg/m3, C2= 180m/s and u2 Homework Equations u1 + P1V1 + (C1)2/2 +...
  5. J

    Using the steady flow energy equation, find the power required

    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...
  6. physea

    B Analyzing open steady flow systems with SFEE vs. Rankine cycle analysis

    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...
  7. JamesB93

    Thermodynamics: SFEE Homework Solution

    Homework Statement This is a question from an exam that my university determined to be so harsh that they allowed resits with uncapped grades. I'm going to be taking such a resit thus I'm trying to figure out the paper: Air at 10oC and 80 kPa enters the diffuser of a jet engine steadily with...
  8. S

    Thermodynamics Energy balance equation for Non - Steady Flow

    Hi, I am currently studying Thermodynamics and stumbled upon this equation and is slightly confused as to how this works. Hopefully someone can help me with the understanding. According to this text here, if I am not wrong e can be h + ke + pe or u + ke + pe depending on where i am looking...
  9. S

    How throttling is a steady flow process?

    If throttling reduces mass flow rate then how can we say it as steady flow process where the mass flow rate is constant?
  10. ltkach2015

    Steady Flow-Does That Mean ALL Properties of Flow are Steady?

    QUESTION: In general: when a flow is considered steady does that mean all properties of the flow are steady? Or: can a flow have steady and unsteady properties?
  11. F

    What is the Outlet Temperature of a Compressed Air Flow?

    Homework Statement Air enters a compressor at 100kPa and 20 oC in steady flow rate . Air is compressed to 1 Mpa. The heat loss is 10% of the power of the compressor . Air enters with speed of 50m/s in a surface of 0,009 m2 and leaves with speed 120 m/s from a surface of 0,0005 m2. Find the...
  12. KingDaniel

    Steady Flow Energy Equation for a Water Pump

    Homework Statement I'm not too sure about my attempt to this question, but what is the simplified Steady Flow Energy Equation for a water pump that has one inlet at the bottom and one outlet at the top, and a work input? Homework Equations Q^ = W^ + m^[(h2 - h1) + 1/2 (c22 - c12) + g(z1 - z2)]...
  13. L

    First law of thermodynamics & steady flow devices

    Homework Statement The motherboard in a laptop is run by a PSU of 20V/4.5A. This motherboard is inside a plastic case where there is not heat transfer through the casing. To stop the motherboard from over heating a single (motherboard powered) 10W electric fan is mounted inside the casing. The...
  14. J

    Aeroengines/Fluid Mechanics - Steady Flow

    Homework Statement See Fig.2.4a, let the gases flowing through the nozzle control volume be perfect with Cp = 1.004kJ/kg.K Determine V9 if T5 = 1000K, T9 = 670K and V5 = 120ms^-1. Homework Equations I've detailed the equations in the attached pdf for clarity. The Attempt at a Solution See...
  15. T

    Effect of distance on jet force

    Homework Statement Apologies for the vague title but I'm not sure how else I could word it, also this isn't really a homework question per se however I'm not too sure where else to ask it. I think it would help if i set up a scenario. Say there was a pipe that released a fluid to a mass...
  16. V

    Accretion for Gamma > 5/3 | Black Hole Solutions

    Hello, I would like to know, what happen with accretion (cloud) when drop toward a black hole. In Bondi case and terminology. If I understand: 1) We describe the cloud falling to star (black hole) by EoS P(\rho)=K\rho^\Gamma . 2) This accretion is steady it means \dot{M}=4\pi r^2u\rho=const...
  17. A

    How Does the Steady Flow Energy Equation Account for Heat Transfer?

    Right, I'm sure this is bread and butter to a lot of you but I have just been introduced to the SFEE. mgz+0.5mC^2+H +Q = mgz + 0.5mC^2 +H+W Where Q is the heat transfer, W is work done and H is enthalpy. Where is it assumed that the heat energy is in the energy balance? If heat is added where...
  18. S

    Sig Figs query for a steady flow pipe

    Homework Statement First let me say I'm new to lab reports at Uni, and I'm dreadful at them... I'm having issues with how many sig figs to correctly display on a data table for an experiment I've done to investigate the Reynolds number. One particular step is to find Δp at different stages on...
  19. E

    Why does a supersonic nozzle have a divergent shape?

    Nozzle: Why for subsonic flow the cross-sectional area of nozzle decreases?
  20. N

    Converging nozzle temperature difference - Steady flow energy equation

    I come from a civil engineering background and I'm about to start a masters in nuclear energy. I have no experience in thermodynamics and I've been doing a bit of revision before the course commences to get me up to speed. I've been working my way through 15 revision questions and I only have a...
  21. Peeter

    Solving Steady Flow b/w Rotating Cylinders

    Homework Statement Consider the steady flow between two long cylinders of radii R_1 and R_2, R_1 > R_1, rotating about their axes with angular velocities \Omega_1, \Omega_2. Look for a solution of the form, where \hat{\boldsymbol{\phi}} is a unit vector along the azimuthal direction...
  22. T

    Comparing Carnot & Ranking Cycles + Steady Flow Energy Equation

    Please i need answer for this questions A- compare the Carnot cycle with the Ranking Cycle B- State The Steady Flow Energy equation and discuss the Origin and definition of each of the terms c- A vapour compression refrigeration using ammonia works at a condenser temperature of 40C and...
  23. W

    Archived Adiabatic expansion in a steady flow question

    I an working on a problem in the text "Mechanics and Thermodynamics of Propulsion" 2e. The problem states a perfect gas with molecular weight M=20 and a specific heat ratio of Y=1.2 expands adiabatically in steady flow from a pressure of 6MPa, a temperature of 3000K, and a velocity of 200 m/s...
  24. D

    Steady Flow Energy Equation Problem.

    Ladies and gentlemen. I have been trying for literally days on this problem and its completley done me in. The problem is as follows. I have to evaluate a jet engine using the SFEE equation. So far I have concluded that this equation will be the best to use... Qr – Wrx = ṁ Δ [ h...
  25. A

    How Does the Steady Flow Energy Equation Apply to an Adiabatic Steam Turbine?

    Homework Statement The power output of an adiabatic steam turbine is 5 MW and inlet and exit conditions are as under Given Inlet Pressure 2MPa Temprature 400 DEGREE CELSIUS Velocity 50m/s Elevation 10m Exit Pressure 15 KPa Temprature 0.9 dry Velocity 180m/s...
  26. D

    Can You Prove the Steady Flow Equation for Ideal Gases?

    Does anybody know how to prove this equation t1/t2 = (p1/p2)^(n-1/n) thanks
  27. N

    How to Calculate Work Transfer in Steady Flow Conditions

    Hi, first post so here goes: I'm having a little trouble with a question on my tutorial, and I am not sure what to do. Here it is: Steam under steady flow conditions has the following states: Initial Conditions: Pressure - 47 Bar Spec Volume - 0.09957 m^3 / kg Internal energy - 3420...
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