MATLAB: How to solve a system of Nonlinear Differential Equations?

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SUMMARY

This discussion focuses on solving a system of nonlinear differential equations using MATLAB, specifically for simulating solid tumor growth. The equations involve five unknowns: f, g, m, p, and n, representing tumor volume fraction, dead tumor tissue fraction, cell chemical potential, cell-to-cell solid pressure, and nutrient concentration, respectively. The equations are derived from the work of Wise et al. and include complex terms such as divergence and gradient operations. The user seeks guidance on implementing these equations in MATLAB to model tumor dynamics effectively.

PREREQUISITES
  • Familiarity with MATLAB programming (version R2021a or later recommended)
  • Understanding of nonlinear differential equations and their applications
  • Knowledge of numerical methods for solving partial differential equations
  • Basic concepts of tumor growth modeling and biological systems
NEXT STEPS
  • Research MATLAB's PDE Toolbox for solving partial differential equations
  • Learn about the finite difference method for numerical solutions of differential equations
  • Explore adaptive multigrid methods for efficient computation in MATLAB
  • Study the Heaviside function and its implementation in MATLAB for modeling discontinuities
USEFUL FOR

This discussion is beneficial for biomedical engineers, mathematicians, and researchers involved in computational biology, particularly those focused on tumor modeling and simulation using MATLAB.

aroniotis
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Hello to everybody,
I'm very new to solving ODES and equations with MATLAB. I have been asked to solve a system of nonlinear equations for simulating the growth of a solid tumor.

Assuming that we have the 5 unknowns which are dxd arrays: f,g,m,p and n.
f(x,t) is the volume fraction of tumor (the fraction of tumor tissue against water and healthy tissue)
g(x,t) is the volume fraction of dead tumor tissue (the fraction of dead tumor cells, i.e. necrotic cells)
m(x,t) is a variable call "cell chemical potential"
p(x,t) is the cell-to-cell solid pressure
n(x,t) is the concentration of nutrients

Then Wise et al (An adaptive multigrid algorithm for simulating solid tumor growth using mixture models, doi: 10.1016/j.mcm.2010.07.007) have derived that the tumor can be simulated by solving the following hard-to-solve system:

(1) df/dt=M*div(f*grad (m))+n*(f-g)-lamdaL*g-div(-grad(p)+m*grad(f))
(2) m=f^3-1.5*f^2+0.5*f-div(grad(f))
(3) dg/dt=M*div(g*grad (m))+heaviside(nN-n)*(f-g)-lamdaL*g-div(-grad(p)+m*grad(f))
(4) -div(grad(p))=n*(f-g)-lamdaL-div(m*grad(f))
(5) 0=div(D*grad(n))+(vp)*(nc-n)-n(f-g)

For outer boundary conditions m=p=q=0, n=1, z*grad(f)=0, where z is the outward pointing unit normal.
(The rest parameters that have not been mentioned are scalars).

Could someone please show me the way how to solve that with Matlab?
 
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