Numerical Method Terminal Velocity

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Ali Enes Yildirim
Ali Enes Yildirim 2017-2-22
评论： Jan 2017-2-27
Parachutist of mass(m) = 68.1 kg
drag coefficient(c) = 12.5 kg/s
g= gravitational acceleration = 9.81
ti=0
vi=0
ti+1 - ti = 0.1
here is the eqn
v(ti+1)=v(ti)+(g-(c/m)*v(ti))*(ti+1 - ti)
I just want to plot within such a point that v(ti+1)-v(t)<0.001
thanks
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Torsten
Torsten 2017-2-23
If you set the initial condition for v to be zero, the solution is v=0 for all times. I guess this is not what you want.
Best wishes
Torsten.
Jan
Jan 2017-2-23
编辑：Jan 2017-2-23
@Torsten: Why?
v(2) = v(1) + (g - (c/m)*v(1)) * 0.1 =
= 0 + (g - 0) * 0.1
This is an acceleration.
@Ali Enes Yildirim: What have you tried so far? The only pitfall if not to confuse the index of the times and the value.

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回答（2 个）

Jan
Jan 2017-2-23
编辑：Jan 2017-2-23
The terminal velocity is reached, when there is no further acceleration. This means that g-(c/m)*v(ti) must be 0.0 and you can calculate the result without any iterations or rough limits.
If you really want to calculate this by a loop:
v(1) = 0;
ti = 1;
tStep = 0.1;
vStep = inf; % Arbitrary large value to allow entering the loop
while vStep > 0.001
... increase ti by 1 (not by 0.1)
... calculate new speed and store it in v(ti) using tStep (not ti)
... calculate the step in the velocity vStep
end
Ali Enes Yildirim
Ali Enes Yildirim 2017-2-23
this is about falling parachutist problem. I solved it with EXCEL by using a lots of rows and columns. ı just wanted make sure whether there is a simple way to solve Numerical Methods with MATLAB. Thank you MS Excel and you guys trying to help me :)

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