I want to solve 4 partial differencial equation with 3 differents variables (Time, Lenght and Radius) using matlab software through PDEPE function or ode15s function.
You may find this answer helpful https://www.mathworks.com/matlabcentral/answers/170648-how-can-i-solve-systems-of-pdes-with-three-independent-variables-by-using-the-pdepe-solver-of-the-ma
Solving partial differential equations (PDEs) with three independent variables in MATLAB can be a complex task depending on the specific form of the PDE. MATLAB provides several functions for solving PDEs, and the choice of method depends on the nature of your problem.
Here's a general outline of the steps you might take:
Define the PDE:Specify the PDE using MATLAB syntax. This involves defining the coefficients and terms of the PDE.
Define the Geometry:Set up the geometry of the problem, including the domain and boundary conditions. MATLAB provides tools for creating 3D geometries.
Discretization:Discretize the problem by dividing the domain into a grid. This involves selecting appropriate discretization methods like finite difference, finite element, or finite volume methods.
Solver Selection:Choose an appropriate solver based on the type of problem and the discretization method. MATLAB has solvers like pdepe for parabolic-elliptic PDEs and pdetool for more complex problems.
Boundary Conditions:Specify the boundary conditions for your problem. This involves defining how the solution behaves at the boundaries of the domain.
Initial Conditions:If your problem is time-dependent, you may need to specify initial conditions.
Solve the PDE:Use the selected solver to numerically solve the PDE. The MATLAB function pdepe is often used for one-dimensional problems, while pdetool or other functions may be suitable for more complex 2D or 3D problems.
Here's a simple example using pdepe for a one-dimensional problem:
matlabCopy codefunction pdex1 m = 0; x = linspace(0,1,100); t = linspace(0,1,10); sol = pdepe(m, @pdex1pde, @pdex1ic, @pdex1bc, x, t); u = sol(:,:,1); surf(x,t,u) title('Numerical solution computed with 20 mesh points'); xlabel('Distance x'); ylabel('Time t'); zlabel('u(x,t)'); end function [c,f,s] = pdex1pde(x,t,u,DuDx) c = 1; f = DuDx; s = 0; end function u0 = pdex1ic(x) u0 = sin(pi*x); end function [pl,ql,pr,qr] = pdex1bc(xl,ul,xr,ur,t) pl = ul; ql = 0; pr = ur - 1; qr = 0; end