Questions tagged [differential-equations]

Questions on the symbolic (DSolve, DifferentialRoot) and numerical (NDSolve) solutions of differential equations in Mathematica.

4,446 questions
Filter by
Sorted by
Tagged with
70 views

Numerical solution to Differential equation

I want to get the differential solution numerically. I used wolfram alpha. here is the link. I tried this code on the Mathematica file. ...
75 views

How Does StreamPlot Handle Singularity or Indeterminates?

I will like to know how StreamPlot finds its way around singular/indeterminate values. Actually, I was thinking of using ...
94 views

Why DSolve gives different answer depending on order of variables: $u(x,t)$ vs. $u(t,x)$?

Using V12 on windows 10. I would think it should not matter if one uses $u(x,t)$ or $u(t,x)$ in the specification of the PDE, as long as everything else is consistent (keeping the initial condition ...
224 views

Problems with solving PDEs

I am using NDSolve to solve the two equations: ...
219 views

Controlling dynamic time step size in NDSolveValue

Statement of problem I'm writing a script to calculate the temperature of a 2D system with time-dependent heat deposition. The heat deposition is a square wave pulse of duration w = 10^-6 seconds, ...
59 views

Implicit function definition and variable change

in my code I solve a non-linear system of ODE to obtain the positive functions RadEnDens and PhiEnDens, everything as a function ...
1k views

How to solve the tsunami model and animate the shallow water wave?

Backslide introduced in 9.0, persisting through 11.3. Recently when I was learning differential equations, I noticed there is a shallow water wave equation to model the tsunami propagation. How to ...
71 views

DSolve returns unevaluated(I need a closed or numerical solution for this system and plot solution)

I am trying to find a solution to this system of differential equations but the program gives the same output without any messages. I would like help. Please find the Mathematica code posted here. a ...
194 views

Thermal conduction (Annulus, 2D): Missing boundary conditions

The thermal conduction problem, described in polarcoordinates can be solved ...
94 views

81 views

Solving system of PDEs with NDSolve

I am trying to solve a system of coupled PDEs with zero-flux boundary conditions on a large domain. I have two problems: 1) Is there a possibility to use results of NDSolve as inititial conditions? ...
40 views

Plotting the solutions of parametric NDSOLVE[] as a function of its parameters

I am trying to solve a 2 set of coupled differential equations one using parametricndsolve and other using *ndsolve . So far I am successful in solving these equations. The solution I found by using ...
140 views

One dimensional heat exchange on a ring: Periodic solution

Subsequent I consider the transient heat exchange problem of a ring in polar coordinates. The ring is heated in a small range 0<\[CurlyPhi]<20° and cooled ...
64 views

Solving a system of linear differential equations [closed]

I am trying to solve a system of linear differential equations, and I am following the instructions given on the Wolfram Alpha page. I am not getting the desired output, as can be seen below: In the ...
47 views

Solution of non linear coupled equations by using shooting, block and StartingInitialConditions

My code is not giving out put. Moreover i do not know how to copy paste this code from my note book. is there any easiest way to paste here. I m plotting graph for the different values of R. I have ...
153 views

How to Solve $y'(x)=x\ln(y(x))$ with $y(1)=1$ using DSolve

The solution to $y'=x \ln(y)$ with initial conditions $y(1)=1$ is $y=1$. How to persuade DSolve to obtain this solution? ...
46 views

Solving coupled differential equations with 4 unknown constants

Recently I just started Mathematica for solving differential equations. Then I tried following 7 coupled differential equations with four unknown constants $(a, b, c, d)$. But after completion of ...
522 views

Finite element heat conduction with coupled 1D and 3D equations

I would like to perform a 3d FEM transient heat transfer in fluid and solid, which should have also included fluid dynamic simulation. But I want to simplify it into a 3d FEM without fluid dynamic ...
86 views

1k views

Using periodic boundary conditions in NDSolve

I need to solve a 2D linear elliptical equation in polar coordinates using NDSolve, but I can’t seem to get Mathematica to accept the required periodic boundary conditions. My actual differential ...
62 views

NDSolve: Boundary conditions not numerical

I am trying to solve coupled differential equations using NDsolve. I am getting an error which says Boundary conditions not numerical. I am not sure about my mistake. Can I get some help? My code ...
84 views

How do I truncate an interpolating function?

I have a very large interpolating function and want access the function at one point in time. I am running out of RAM running ...
82 views

Using ParametricNDSolve with n subscripted functions

I want to calculate trajectories of an n-pendulum. For the number n=1 it's just a pendulum, for n=2 a double pendulum , for n=3 a triple and so on. The Solver has to solve n equations for the angle. ...