## Using ode45 for transient analysis

Asked by louis marie

### louis marie (view profile)

on 7 Apr 2019
Latest activity Answered by Torsten

### Torsten (view profile)

on 8 Apr 2019
Accepted Answer by Torsten

### Torsten (view profile)

Hi,
Quite inexperinced with MATLAB so apologies if the question is obvious but:
I need to use matlab to do a transient analysis of a mixed mode heat transfer (radiation and convection), and calculate time taken for a mass of water to increase to a certain temperature. As temperature increases it changes the heat transfer properites.
The equation I'm trying to use to calculate time is as follows:
dt = (Mw * Cw * dT)/(Adisc * (e*(q2 + q3 - (2 * sig * T^4))-(alp2 + alp3)*(T - Tamb)))
Everything is a constant except 'T' which is the water temperature and will vary while the water is heated. Now my problem is using ode45, because it appears I need to input a time span 'tspan':
[t,y] = ode45(odefun,tspan,y0)
This 'tspan' requires the final time, however, I am obviously trying to calculate the final time so not sure how I should be doing this.
Any help apreciated.

R2014b

on 8 Apr 2019