Physical meaning of 3 order spatial derivative?

Click For Summary
SUMMARY

The equation \(\frac{\partial u}{\partial t}+\bar{U}\frac{\partial u}{\partial x}=D\frac{\partial ^3 u}{\partial x^3}\) represents a linearized form of the Korteweg-deVries (KdV) equation, which models surface waves in fluid dynamics. This equation can describe the transient convection and diffusion of a species in a flowing stream, where \(U\) denotes the stream velocity and \(D\) is the diffusion coefficient. The third-order spatial derivative indicates the gradient of curvature, relevant in various physical systems, particularly in unsteady hydrodynamic boundary layers.

PREREQUISITES
  • Understanding of partial differential equations (PDEs)
  • Familiarity with the Korteweg-deVries equation
  • Knowledge of fluid dynamics concepts, particularly convection and diffusion
  • Experience with Eulerian and Lagrangian frames of reference
NEXT STEPS
  • Research the applications of the Korteweg-deVries equation in modeling nonlinear waves
  • Study the physical implications of third-order spatial derivatives in fluid dynamics
  • Explore the concept of unsteady hydrodynamic boundary layers in fluid mechanics
  • Learn about the mathematical techniques for solving partial differential equations
USEFUL FOR

Physicists, fluid dynamicists, and applied mathematicians interested in wave dynamics, convection-diffusion processes, and the mathematical modeling of physical systems.

jollage
Messages
61
Reaction score
0
Hi

Does anybody know the physics meaning of the following equation

\frac{\partial u}{\partial t}+\bar{U}\frac{\partial u}{\partial x}=D\frac{\partial ^3 u}{\partial x^3}

Is there any physical system can be described by this equation?

Thanks.
 
Physics news on Phys.org
The 1st order is the gradient
The 2nd order is the curvature
The third order is... ? That the jist of the question ?

note - you normally find the equation from the physics, not the other way around.
There are probably, after all, many situations where you'd want to find the gradient of the curvature.
 
jollage said:
Hi

Does anybody know the physics meaning of the following equation

\frac{\partial u}{\partial t}+\bar{U}\frac{\partial u}{\partial x}=D\frac{\partial ^3 u}{\partial x^3}

Is there any physical system can be described by this equation?

Thanks.
That is one form (the linearized form) of the Korteweg-deVries equation, and can be used to model surface waves. Other 'flavors' of the KdV equation are used to model nonlinear waves in a dispersive-dissipative medium. Including other spatial dimensions allows you to model unsteady hydrodynamic boundary layers.
 
If u is the concentration of a diffusing species, this equation describes the transient 1D convection and diffusion of the species in a flowing stream. In this application, U is the velocity of the stream in which the species is dissolved, and D is the diffusion coefficient. The flow is in the x-direction. The problem is set up using an Eulerian frame of reference.

Chet
 
I do not have a good working knowledge of physics yet. I tried to piece this together but after researching this, I couldn’t figure out the correct laws of physics to combine to develop a formula to answer this question. Ex. 1 - A moving object impacts a static object at a constant velocity. Ex. 2 - A moving object impacts a static object at the same velocity but is accelerating at the moment of impact. Assuming the mass of the objects is the same and the velocity at the moment of impact...

Similar threads

  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 0 ·
Replies
0
Views
422
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
Replies
5
Views
4K
  • · Replies 2 ·
Replies
2
Views
598
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 4 ·
Replies
4
Views
2K