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Showing results 1 to 11 of 11 Search took 0.00 seconds. Search: Posts Made By: FMDenaro

Forum: Main CFD Forum May 3, 2017, 11:22

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro Of course, do not forget you will see a slope... Of course, do not forget you will see a slope increased by the O(dt)

Forum: Main CFD Forum May 3, 2017, 02:52

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro Yes, the slope seems to indicate also less than... Yes, the slope seems to indicate also less than first order of accuracy. The CFL (the ratio dt/dx) says the way in which you evaluate the local truncation error that is a function of the...

Forum: Main CFD Forum May 2, 2017, 17:08

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro Use a finer spatial grid step (for example 10^-3)... Use a finer spatial grid step (for example 10^-3) and check the slope at smaller time steps. The convergence to the correct slope is never reached monotonically...

Forum: Main CFD Forum May 2, 2017, 16:46

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro But for grid size you are denoting the time step,... But for grid size you are denoting the time step, right? why the scale is 10 up to 10^2? If you have a second order spatial accuracy you get in the LTE a term O(10^-5). I suggest to use a more...

Forum: Main CFD Forum May 2, 2017, 14:28

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro First, I strongly suggest to represent the... First, I strongly suggest to represent the numerical solution only with symbols, not with continue lines. That will help the visualization. How fine is the spatial grid? Then, I do not understand...

Forum: Main CFD Forum May 2, 2017, 02:59

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro The order of the accuracy can be evaluated if all... The order of the accuracy can be evaluated if all the terms of the local truncation error vanish simultaneously, therefore one performs a grid refinement by taking CFL=constant. If you want check...

Forum: Main CFD Forum May 1, 2017, 18:03

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro First, set the initial condition at x=0 and fix a... First, set the initial condition at x=0 and fix a domain quite long from -L to +L such that you can evolve the solution without entering BC.s. Then, to check the accuracy order you have to take...

Forum: Main CFD Forum May 1, 2017, 17:35

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro Why do not use an initial smooth function like a... Why do not use an initial smooth function like a gaussian centered at x=0? you can just let to evolve towards +/- x direction. This way you can check the orde of accuracy in time and space.

Forum: Main CFD Forum May 1, 2017, 17:15

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro I don't understand ...you have a linear PDE... I don't understand ...you have a linear PDE describing a couple of travelling waves at +/-c. The initial/boundary conditions define the presence or not of the travelling discontinuity along x....

Forum: Main CFD Forum May 1, 2017, 16:32

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro You wrote: "Specifically, I want to... You wrote: "Specifically, I want to propagate an exponential decay shock wave in a 1D shock tube "

Forum: Main CFD Forum May 1, 2017, 15:18

Replies: 20 Time integration order of accuracy when solving acoustic wave equation using FEM Views: 1,888 Posted By FMDenaro Theoretically, you cannot perform an accuracy... Theoretically, you cannot perform an accuracy test for a case where the solution is singular... the accuracy test has the aim to evaluate the order of the magnituted in the leading term appearing in...

Showing results 1 to 11 of 11

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