1 / 10

Fluid Flow: Steady Flow

Fluid Flow: Steady Flow. Objectives. Section 5 – Fluid Flow Module 4: Steady Flow Page 2. U nderstand steady flow. Identify the types of steady flow. Examine the considerations for steady flow. S tudy the Navier-Stokes Equation for steady flow. Learn from two examples:

leone
Download Presentation

Fluid Flow: Steady Flow

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Fluid Flow: Steady Flow

  2. Objectives Section 5 – Fluid Flow Module4: Steady Flow Page 2 • Understand steady flow. • Identify the types of steady flow. • Examine the considerations for steady flow. • Study the Navier-Stokes Equation for steady flow. • Learn from two examples: • CFD Analysis of Couette Flow • Flow between two fixed parallel plates

  3. Steady Flow Section 5 – Fluid Flow Module4: Steady Flow Page 3 • A steady flow is one in which the conditions (velocity, pressure and cross-section) may differ from point to point but DO NOT change with time. • In steady flow, all time derivatives in the governing equations are removed. • Compared to unsteady flow, steady flow is computationally less expensive and therefore much faster to solve.

  4. Steady Flow Types Section 5 – Fluid Flow Module4: Steady Flow Page 4 • Steady flow can be further classified into steady uniform flow and steady non-uniform flow. • Steady uniform flow: • Conditions do not change with position in the stream or with time. An example is the flow of water in a pipe of constant diameter at constant velocity. • Steady non-uniform flow: • Conditions change from point to point in the stream but do not change with time. An example is flow in a tapering pipe with constant velocity at the inlet. Velocity changes as fluid moves along the length of the pipe toward the exit.

  5. Considerations for Steady Flow Section 5 – Fluid Flow Module4: Steady Flow Page 5 • For all steady state flow cases, the total amount of flow entering into the system must have an outlet boundary that would allow the same amount of fluid out. • If this is not done, the solution will either fail to converge or circulation will occur at the inlet boundary. • Mass flow conservation as well as energy conservation should be ensured for the domain. Flow out Flow in Flow out Flow out

  6. Navier–Stokes Equation for Steady Flow Section 5 – Fluid Flow Module4: Steady Flow Page 6 The time derivative is set to zero, thus simplifying the calculation. 0 The most simplified cases of CFD are incompressible steady state flow with no body forces, as the terms inside the Navier–Stokes Equation are reduced.

  7. Video Example: CFD Analysis of Couette Flow (Steady State) Section 5 – Fluid Flow Module4: Steady Flow Page 7 • The CFD analysis of Couette flow using Autodesk Simulation Multiphysics has been described in a two-part video: • The first part explains the problem, setting up of the flow domain, meshing and application of boundary conditions. • The second part explains the analysis and post processing, covering the details of equation solving in the background and display of the analysis results. Y u0 Moving Plate X Stationary Plate

  8. Additional Example:Flow Between Two Fixed Parallel Plates Section 5 – Fluid Flow Module4: Steady Flow Page 8 • Flow between two fixed parallel plates • Couette flow case can be used • Setting up geometry and walls can be fixed • Distance between the plates is 2Y • The velocity can be defined as: • Maximum Velocity will occur at the center, i.e., at y =0 y Y x Exact Solution These two exact solution equations can be used by students to verify results from CFD.

  9. Summary Section 5 – Fluid Flow Module4: Steady Flow Page 9 • Steady flow is when flow behavior(velocity, pressure) does not change with the passage of time. • Many real life studies are carried out assuming steady flow. • Even when studying unsteady flow, it is a common practice to carry out a steady state analysis first.

  10. Summary Section 5 – Fluid Flow Module4: Steady Flow Page 10 • For example, study of flow across a vehicle is carried out in steady state to evaluate the drag coefficient. • It is important that the boundary conditions are set up for steady flow such that the continuity is maintained and changes with time inside the domain are zero. • Otherwise, the numerical analysis may diverge.

More Related