Questions tagged [computational-physics]

Questions with this tag should be about computational physics, which is the study of physical situations with the use of software (commercial or in-house). Please note that details of writing and/or debugging code is OFF-TOPIC and should be asked at either Computational Science, Code Review or Stack Overflow.

Questions with this tag should be about computational physics, which is the study of physical situations with the use of software (commercial or in-house). Computational physics covers a wide range of subjects, such as , , and , among many others.
This tag should not be applied if your question is about computing a value without the use of a computer.

Types of questions we can answer here

  • We can advise on numerical methods when tied to a physical problem and not a generic P/ODE (e.g., What methods would one use to solve diffusion problems?)
  • We can discuss scheme quality/limitations (e.g. What makes the original Murman-Cole scheme not conservative in transonic potential flows?)
  • We can discuss scheme design (e.g., How does one determine if a scheme is conservative?)

Types of questions we cannot answer here

  • We cannot answer programming questions (e.g., How does one implement X method for Y equation?)
  • We cannot debug code (e.g. I programmed Crank-Nicholson but it's not working, what did I do wrong?)
  • We cannot optimize code (My matrix inversion routine used for Crank-Nicholson is running slow, how can I speed it up?)
  • We cannot advise on libraries/languages/compilers/etc (e.g. Should I use PETSc or Trillinos for my code? or Is Fortran better for scientific programming?)
  • We cannot recommend software (e.g., What software can solve the diffusion equation?)

In general, if your question is about writing compiling, debugging or optimizing a piece of code or is about a specific language or library, then it is off topic on Physics but may be on-topic on programming-oriented Stack Exchange sites such as Computational Science, Code Review or StackOverflow. For some third-party languages and libraries, there may be specific user forums that would also be an appropriate venue.

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Feynman's infinite amount of logic for one tiny bit of space

Watching one of Feynman's lectures, I came across something that puzzled me. What was Feynman referring to when he said the following? What goes on in no matter how tiny a region of space and no matter how tiny a region of time, according to the…
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Adding rotation to internal coordinates

I'm optimizing the geometry of a system composed of several interacting masses (a molecule). The energy of the system depends on the relative position of the masses, and all velocities are zero. In a simple case, the energy is invariant with…
Jellby
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Future Computer Performance

Moore's law has succesfully predicted up to now that integrated circuit transister density doubles every two years. However, computer performance is dependent on additional factors like architecture, chip design and software. What physics-related…
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Is Bremermann's limit redundant with Landauer's limit for all practical purposes?

Trying to understand the physical limits to computation, I notice that among these we have two types of limits that constrain the minimum allowable energy for a computation. Limits that constrain the product of energy and time taken, which include…
Alan Rominger
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Why are Markov chains better than naive algorithm for Random picking?

I have a question about the problem of coming up with a random distribution of non-overlapping coins in a given two dimensional space. I don't understand why using the random sequential adsorption technique (picking an initial random position for…
user34801
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What does it mean for equations to have not advanced to the point where one could plug them into a computer?

In this article about the EMC effect (in no way relevant to my question), the statement is made: The problem is that the complete QCD equations describing all the quarks in a nucleus are too difficult to solve, Cloët and Hen both said. Modern…
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fun computational physics projects

I want to learn how to code in Java and am in need of some cool computational physics projects that would provide motivation to do so. I was wondering if you guys could list some medium-level computational physics projects (from any field) that you…
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Boundary conditions and density when using smoothed particle hydrodynamics/corrective smoothed particle method for two-temperature models

I am trying to solve the dual-hyperbolic two temperature model (TTM) using a modified smoothed particle hydrodynamics (SPH) scheme known as CSPM (corrective smoothed particle method), as demonstrated in these two papers (can't add links,…
Ash
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Is there any untamed physics in the CPU?

In a x86/amd64 CPU could I find an instruction or a combination of instructions that leak inside the system? Could some other physics properties (not accounted by the design) be measured or interacted with?
dddvvv
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Non-computable numbers in Physics

It is known that there are real numbers that can't be calculated (non-computable numbers). Quite probably that some physical phenomena (it is possible still undetected) depend on this numbers. Whether means it, what we can't construct the theory of…
maksb
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Why do people use C++ in Computational Physics?

Once day, I talked to my Prof. about Computational Physics and he showed me his work. I'm quite surprised that why Prof. use C++ for computation because C++ quite complicated. I heard he talked about memory talk about pointer. Why didn't he use…
fronthem
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Optimal configuration of particels connected by springs

I try to find the optimal configuration of points on a grid, which has to fulfill some constraints. Solving a problem with points on a grid and finding the optimal configuration is a discrete optimization problem. Since my current approach (using…
nuemlouno
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Trajectory in a discrete field

I am not sure if this question is more maths, physics, or computer science, but here we go. Let's say we have a scalar field $\phi(\vec{x}): \mathbb{R}^2 \rightarrow \mathbb{N}$ but we only have information of some points of $\vec{x}$, although we…
Ax11
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Equations for implementing a 2D FDTD plane wave incident at an oblique angle with Bloch periodic boundary conditions

I am interested in modeling a periodic device via 2D Finite Difference Time Domain method (FDTD), in order to calculate the reflection and transmission from a single-frequency plane wave incident at a variety of angles. I implemented a 2D FDTD in…
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Finit element modelling of rigid bodies and machining

I would like to computer model of material machining. Is finite element metod suitable for this? I am imagining 3D grid of voxels, which are tracking matter properties across space. Is this correct idea? What are correct terms for this to google…
Dims
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