2-D Unsteady State Heat Conductivity

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Discussion Overview

The discussion centers on the challenges of implementing a finite element analysis for unsteady state heat conductivity in two dimensions, focusing on time-dependent problems. Participants explore the transition from steady-state to unsteady-state algorithms, particularly using explicit Euler time marching methods.

Discussion Character

  • Exploratory
  • Technical explanation
  • Homework-related

Main Points Raised

  • One participant seeks assistance in translating a C++ program from 2-D steady state heat conductivity to an unsteady state version, expressing a preference for simplified explanations.
  • Another participant inquires about the specifics of the steady-state code's solution method, noting that many solvers utilize a pseudo-time approach.
  • A participant mentions using a preconditioned conjugate gradient solver for the steady-state code and expresses a desire to implement the explicit Euler time marching algorithm, but lacks a lumped capacity matrix.
  • Another participant raises a question about the relationship between Gaussian quadrature and time-marching algorithms in the context of finite element solutions for 2-D heat conductivity problems.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the specifics of the unsteady state algorithm or the role of Gaussian quadrature, indicating that multiple competing views and uncertainties remain in the discussion.

Contextual Notes

There are limitations regarding the assumptions made about the algorithms and the specific requirements for implementing the explicit Euler method, as well as the dependence on the definitions of terms like "lumped capacity matrix" and "Gaussian quadrature." Unresolved mathematical steps may also exist in transitioning from steady to unsteady state.

dinaharchery
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Hello all,

I am not an engineer but am trying to learn finite element analysis for solid materials - in particular heat conductivity for time dependent problems in 2-D for a single material. I am interested in the explicit Euler time marching, thus I believe I need a lumped capacity matrix?

I have finished a C++ program using 2-D Steady state heat conductivity, it is very simple (as I said I am not an engineer). Can anyone assist me in translating a 2-D code for steady state heat conductivity to a unsteady state (time dependent) version? Small words please :smile: , I am a computer scientist.

Thanks for any help.
 
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Any idea at all? A simple 2-D unsteady state algorithm?

Thanks again
 
How exactly does your steady-state code compute the solution? Many solvers like this use some sort of pseudo-time, whether you want to call it iterations, or time-steps or whatever.
 
The steady-state code uses a preconditioned conjugate gradient solver, so the solver itself is iterative. I would like to use the explicit euler time marching algorithm but I currently do not have a lumped capacity matrix.
 
I have been doing some research into the unsteady state heat for finite element analysis and have run across Gaussian quadrature. Can anyone explain how this relates to a time-marching algorithm for the FE solution to a simple 2-D (x and y) heat conductivity problem:confused:?

Thanks.
 

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