cfd techniques quiz n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
CFD Techniques Quiz PowerPoint Presentation
Download Presentation
CFD Techniques Quiz

Loading in 2 Seconds...

play fullscreen
1 / 30

CFD Techniques Quiz - PowerPoint PPT Presentation


  • 109 Views
  • Uploaded on

CFD Techniques Quiz. What is the weight of an adult hippo skin?. 0.5 tons 1 ton 2 tons. 10. What type of equation is this if the flow is supersonic?. elliptic parabolic hyperbolic. 10.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'CFD Techniques Quiz' - lara


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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide4
What is X in the definition below?The X is the difference between the PDE and the finite difference representation
  • Rounding error
  • Goodness of fit
  • Truncation error
  • Convergence measure
  • Marching error

10

consider the finite difference approximation to the first derivative below which statement is false
Consider the finite difference approximation to the first derivative below. Which statement is false?
  • If the grid spacing is halved the error goes down by 1/4
  • This is a central difference approximation
  • This form might be useful close to a wall
  • This form might be useful near the edge of the simulation

10

slide6

What is X in the description below?A X is one for which errors from any source (round-off, truncation, mistakes) are not permitted to grow in the sequence of numerical procedures as the calculation proceeds from one marching step to the next.

  • consistent numerical scheme
  • stable numerical scheme
  • convergent numerical scheme
  • second-order numerical scheme

10

slide7

What is X in the description below?A solution to a finite difference representation is said to be X if it approaches the true solution to the PDE having the same initial and boundary conditions as the mesh is refined.

  • consistent
  • stable
  • convergent
  • Ill-posed

10

slide8

What is X in the description below?By X, we mean those errors that arise as a result of the rounding to a finite number of digits in the arithmetic operations.

  • truncation
  • round-off errors
  • systematic errors
  • happy accidents

10

slide9

What is X in the definition below?A finite difference representation is said to be X if we can show that the difference between the PDE and its finite difference representation vanishes as the mesh is refined.

  • consistent
  • convergent
  • stable
  • first order
  • most excellent

10

which statement is false
Which statement is false?
  • Parabolic equations have degenerate characteristics
  • The initial value problem is ill-posed for elliptic problems
  • Discontinuities can appear in elliptic problems
  • The unsteady heat conduction equation is an example of a parabolic problem

10

slide11

What is X in the definition below? X error is the error in the solution to the PDE subject to the given initial values and boundary conditions caused by replacing the continuous problem by a discrete one and is defined as the difference between the exact solution of the PDE (round-off free) and the exact solution to the finite difference equations (round-off free).

  • Discretisation
  • Truncation
  • Round-off
  • Integration

10

which statement is false1
Which statement is false?
  • The Courant number has no units
  • If you double the sound speed, the Courant number doubles
  • If you halve the space grid the Courant number doubles
  • If you halve the time grid, the Courant number doubles

10

which term would not be required in a von neumann stability analysis of the equation below hint
Which term would NOT be required in a von Neumann stability analysis of the equation below? Hint:

1.

2.

3.

4.

5.

10

slide14

The amplitude in a von Neumann stability test is found to have the following modulus. What can we say about the finite difference representation?

  • It’s unconditionally stable
  • It’s conditionally stable
  • It’s conditionally unstable
  • It’s unconditionally unstable

10

what is the equilibrium value of a in the square grid used to solve laplace s equation in 2 d
What is the equilibrium value of A in the square grid used to solve Laplace’s equation in 2-d?
  • 2.3
  • 2.4
  • 2.5
  • 2.6
  • 2.7

10

which of these is the correct expression for the iteration at point 3 in an explicit jacobi method
Which of these is the correct expression for the iteration at point 3 in an explicit (Jacobi) method?
  • 1.
  • 2.
  • 3.
  • 4.

10

slide22
Which of these is the correct expression for the iteration at point 2 in an implicit (Gauss-Seidel) method?
  • 1.
  • 2.
  • 3.
  • 4.

10

a solution of this equation is which way is the wave travelling and what is its speed
A solution of this equation is Which way is the wave travelling and what is its speed?
  • Left to right (toward positive x) speed 2
  • Right to left (toward negative x) speed 2
  • Left to right (toward positive x) speed 0.5
  • Right to left (toward positive x) speed 0.5

10

which of the following statements is false
Which of the following statements is false?
  • Dispersion is caused by odd derivative terms in a PDE truncation
  • Diffusion is caused by odd derivative terms in a PDE truncation

10

slide28
A CFD simulation of a shock develops ‘waviness’ as pictured below? This is evidence for what in the solution?
  • Dispersion
  • Diffusion

10

slide30

Which of these is NOT a point at the entry to the duct (x=0) joined to the point P by 45 degree characteristics (i.e. lines of slope -1 and +1) ?

  • (0,0.6)
  • (0,-0.6)
  • (0,0.4)
  • (0,-0.4)

10