Unable to solve a nonlinear DE analytically help needed

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In summary, the conversation discusses the need for an analytic solution for a nonlinear differential equation and the attempted transformation to simplify it. However, the simplified DE could not be solved and the conversation ends with a request for a more sophisticated solution.
  • #1
motavassely
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Hi all,

I have a nonlinear differential equation and I need to find an analytic solution for it. Here it is:

[tex]\ddot{S}=-{1 \over 6} \dot{S}-{2 \over 7}(1-S)^2(- \dot{S})^{1.3}[/tex]

I have used a transformation to simplify it:

[tex]-\dot S = v[/tex]

and came up with this DE which I couldn't solve it:

[tex]{{dv} \over {dS}} ={1 \over 6} - {2 \over 7} (1-S)^2 v ^ {0.3}[/tex]

Anyone who can solve them?

Bests,

Ali
 
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  • #2
shouldnt you have

[tex]{{dv} \over {dS}} ={1 \over 6}v - {2 \over 7} (1-S)^2 v ^ {0.3}[/tex]
 
  • #3
Unfortunately not. It's not a Bernoulli? DE.
 
  • #4
motavassely said:
Hi all,

I need to find an analytic solution for it.

[tex]S(t)=k[/tex]
 
  • #5
a bit more sophisticated solution, please!
 

1. What is a nonlinear differential equation?

A nonlinear differential equation is an equation that involves nonlinear terms, meaning that the dependent variable and its derivatives are not simply proportional to each other. In other words, the rate of change of the dependent variable is not directly proportional to its current value.

2. Why is it difficult to solve a nonlinear differential equation analytically?

Unlike linear differential equations, there is no general method for solving nonlinear differential equations analytically. This is because nonlinear equations often have complex and unpredictable solutions, making it challenging to find an explicit expression for the solution.

3. What is the difference between analytical and numerical solutions?

An analytical solution is a closed-form solution that can be expressed using a finite number of standard mathematical operations, such as addition, subtraction, multiplication, division, and exponentiation. A numerical solution, on the other hand, is an approximate solution that is obtained using numerical methods, such as Euler's method or Runge-Kutta methods.

4. Can nonlinear differential equations be solved using numerical methods?

Yes, numerical methods can be used to solve nonlinear differential equations. These methods involve breaking the problem down into smaller, simpler steps and using numerical techniques to find approximate solutions. However, the accuracy of the solution depends on the chosen method and the step size used.

5. What are some real-world applications of nonlinear differential equations?

Nonlinear differential equations have numerous real-world applications, including in physics, biology, economics, and engineering. For example, they can be used to model the growth of a population, the spread of diseases, the motion of a pendulum, and the behavior of electric circuits. Nonlinear differential equations are also essential in control theory, which is used to design systems such as autopilots and robots.

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