Recent content by jollage

Hi, I would like to use the 2/3 padding rule for the dealiasing. In 1D, it's straightforward. For 2D, do I just have to set the highest 1/3 frequency components zero in both directions? For example, I ffted a 7*7 real data in Matlab, then I set the 4th and 5th columns and rows (corresponding...

Great, thanks. Is there any general procedure of changing the parameters to achieve this (fixing the value of a_n)? For instance, for fixing a_1=0, what I usually do is to plot a neutral curve in the parameter space, and then to choose the parameters on that neutral curve. This will guarantee...

Hi pasmith, Thanks a lot for your reply. Yes, you are right. For the GLE, I should add some spatial-derivative terms. Here, I just listed the linear and nonlinear growth rate terms, since they are pertaining to the questions I have. I understand what you wrote there. Do you have any clue...

Hi all, I am not familiar with the dynamic system theory. When I was trying to understand the weakly nonlinear stability analysis, I realize the following question. It is known that the center manifold reduction can be used to study the first linear bifurcation. This lead to the...

Hi, I'm majoring in fluid mechanics. I notice some researchers are using the phrase parametric instability. I googled it, it seems this comes from the solid mechanics (vibration). Can you explain to me what's the difference between parametric instability and the resonance? They seem the same...

Yes, I assume so. That's my question. I don't know which type of polymer should be used. Do you know where I can find this information?

I want to know if this is possible. I'm afraid the polymer is not polarizable, or a very high electric field is required to polarize the polymer molecules.

Hi, I'm thinking the following scenario. I have some solution in a container, where polymers are dissolved inside. If left so, the polymer will be homogeneous in the liquids. Now I add an electric field on the two sides of the container, will the polymers be polarized and stretched? So the...

Thank you Bystander. These seem very interesting. I checked quickly the levitating frog, I read "...Frogs are convenient (for the experiments) not only because they have a high water content, which is a good diamagnetic material...", so it seems convinced that if one applies a strong enough...

I was thinking something like molted iron or metal, that's also my question, I'm not sure what it could be. I want to know whether the liquid could be held up only by the magnetic field or electric field.

Hi, Would it be possible to hold electrified liquids in the air? There is an external electric field applied to the liquids. What kind of liquid must it be? I guess water wouldn't do the job.

Thanks. I see. Could tell me any references on the energy evolution of the lower orders? I want to see how people deal with the evolution of the \epsilon^3 or \epsilon^4 order in the following u^2 = U^2 + 2\epsilon U u_1 + \epsilon^2(u_1^2+2U u_2) + 2\epsilon^3 u_1 u_2 + \epsilon^4 u_2^2 under...

Thanks a lot for your reply, the_wolfman. I was participating a meeting, sorry to reply late. What you wrote there brings me to think whether the energy analyses we are talking about are the same thing. I am studying turbulence and the transition to turbulence. There, the hot topic is the flow...

Hi the_wolfman, Thanks for your comments. (1) Yes, you are right, in the title I'd better remove "linear" (2) & (4) It's my fault not being clear. But the operator ##\mathcal{L}## actually includes ##u_0 u_1## you've pointed out (because I assume all the linear part of ##u_1## is absorbed in...

Hi, I'm considering the energy evolution of variables of different orders in a partial differential equation. The PDE is nonlinear, which can be written as ## \frac{\partial u}{\partial t} = \mathcal{N}u ## where ##\mathcal{N}## is a nonlinear operator in space and time. Now I want to check...