What is the most difficult topic in PDE?

In summary, the topics generally considered more challenging in a PDE course are time dependent PDEs, systems of PDEs, and non-linear PDEs. Solving PDEs can be challenging due to the need for making approximations and using numerical methods. Some specific topics that may be more difficult include Bessel functions, Fourier analysis, and special cases of the Navier-Stokes equations. Concepts such as convolution, unit-step functions in Laplace, and dirac delta are also used in PDEs. However, it is best to approach each topic as it comes and focus on understanding the material rather than stressing about which topics may be more challenging.
  • #1
Dens
74
0
I am taking it in a few weeks, could someone tell me which topic are generally more challenging? PDE is Partial Differential Equations.

Thank you
 
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  • #2
As with ODEs, one starts with relatively simple PDEs and moves up to more complex equations and systems of equations.

In order of complexity, time dependent PDEs, and then systems of PDEs, and finally non-linear PDEs.

Just relax and enjoy.
 
  • #3
Dens said:
I am taking it in a few weeks, could someone tell me which topic are generally more challenging? PDE is Partial Differential Equations.

Thank you

Navier Stokes or MHD Equations are unsolvable as far as I know.
 
  • #4
MHD equations are solvable via linear perturbation. You throw away every term that's nonlinear! But overall, most PDEs are not solvable in nature without making approximations.

Transport equations can generally be solved only using numerical methods.

As for the actual course itself, I'd have to say that the Bessel functions always got me the best of me when I took my first course in PDE.
 
  • #5
Well there a lot of unsolved problems in PDEs. I would say those are quite card.
 
  • #6
Dens said:
I am taking it in a few weeks, could someone tell me which topic are generally more challenging? PDE is Partial Differential Equations.

Thank you
If it's a standard first quarter/semester course for me the most difficult aspect was Fourier analysis due to the different types of convergence. I had not taken real analysis so learning about uniform, pointwise and L convergences was more challenging the rest of the material.

Otherwise, solving PDE's (in an intro course) is pretty easy. If it's fairly standard, you'll probably cover the wave equation on the full line, diffusion equation on the full line, separation of variables and laplaces equation + a few other topics your instructor will pick that probably differ from person to person.
 
  • #7
clope023 said:
Navier Stokes or MHD Equations are unsolvable as far as I know.

Some useful special cases of the Navier-Stokes equations are solvable analytically.
 
  • #8
To me, knowing which topic in a class is more challenging is actually hindering. You get worked up thinking about how you will tackle this topic differently than the others and stress yourself out. The best way to go about it is taking the topics as they come, read the relevant material, and work on practice problems until you can solve the problem without any pain or suffering (outside of wrist pain).
 
  • #9
Is the concept of "Convolution", "unit-step functions in Laplace", or "dirac delta" heavily used in PDE? It's an intro class by the way...
 
  • #10
Dens said:
Is the concept of "Convolution", "unit-step functions in Laplace", or "dirac delta" heavily used in PDE? It's an intro class by the way...
It's not like those are separate chapters in books. Convolutions comes up, heavyside functions come up and sometimes you want to take their laplace transform, the dirac delta function comes up, etc, etc. They're used, yeah.

That being said, that sounds more like 2nd semester stuff.
 
  • #11
Dens said:
Is the concept of "Convolution", "unit-step functions in Laplace", or "dirac delta" heavily used in PDE? It's an intro class by the way...

They all come up. The standard euristic solution to the cauchy problem for heat equation IS a convolution of. The dirac delta comes up especially if you mention distributions, so pretty much everytime you hear about "fundamental solution(s)" etc.
 

1. What is the most common type of PDE?

The most common type of PDE is the linear second-order PDE, which includes the popular heat, wave, and Laplace equations. These equations are used to model physical phenomena such as heat diffusion, sound waves, and electrostatics.

2. What makes PDEs difficult to solve?

PDEs are difficult to solve because they involve multiple independent variables and their derivatives. This makes it challenging to find exact solutions, and numerical methods must be used instead. Additionally, PDEs can exhibit complex behavior such as shock waves and oscillatory solutions, making them even more challenging to analyze.

3. What is the most difficult topic in PDE to understand?

The answer to this question may vary, as different people may find different topics more challenging. However, one of the most difficult topics in PDE is the theory of existence and uniqueness of solutions. This theory deals with proving the existence of a solution for a given PDE and determining if it is unique.

4. What are some common techniques used to solve PDEs?

Some common techniques used to solve PDEs include separation of variables, Fourier series, Laplace transforms, and numerical methods such as finite difference and finite element methods. These techniques allow for the transformation of the PDE into a simpler form that can be solved using algebraic or numerical methods.

5. How are PDEs used in real-world applications?

PDEs have a wide range of applications in physics, engineering, and other fields. They are used to model and understand various physical phenomena, such as heat transfer, fluid dynamics, and electromagnetic fields. PDEs are also crucial in the development of new technologies, such as predicting weather patterns and designing airplane wings.

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