清空筛选条件
清空筛选条件

ODE45 running infinitely without solving

2 次查看（过去 30 天）
Ajmal R S
Ajmal R S 2020-5-4
评论： Ajmal R S 2020-5-5
I tried to code an ode45 function to find the concentration wrt to thickness of membrane but the ode45 function is taking too long without actually solving the code
ts = 100e-06; %in m
ta = 100e-09; %in m
z0 = ta + ts ; %z = ta+ts
zend = ta + ts + del_d ; %z = ta+ts+delta_d
[zdsol,cdsol]=ode45(@(z,c) decp(z,c), [z0,zend],c0);
And this is the function
function dc = decp(z,c)
x1_dsd = -6.92e-12;
x2_dsd = -9.95e-11;
x3_dsd = 1.51e-9;
dsd_d= x1_dsd*c^2 + x2_dsd*c + x3_dsd;
dc = ((0.02+6*c)/dsd_d);
end
With Js and Jw being constants
Please help !

请先登录，再回答此问题。

采纳的回答

Walter Roberson
Walter Roberson 2020-5-5
编辑：Walter Roberson 2020-5-5
try ode23s. if your system is stiff then ode45 can take a long long time.
Also I worry that your c0 is associated with time 0; it needs to be associated with time z0 instead.
Your denominator dsd_c has zeros near time 1e-11 which could be a problem
  5 个评论
显示 3更早的评论
Ajmal R S
Ajmal R S 2020-5-5
Here is the full code.
clc;
clear all;
A = 0.5;
B = 0.4;
S = 200e-06;
Jw= 6;
Js= 0.02;
c0 = 1;
v = 20; %cross flow velocity feed and draw in cm/s
x1_rho = 0.04;
x2_rho = 1;
rho_d = x1_rho*c0 + x2_rho; %in cgs
x1_mu = 0.02;
x2_mu = 0.06;
x3_mu = 0.89;
mu_d = x1_mu*c0^2 + x2_mu*c0 + x3_mu; %in cgs
L = 8.55; %channel length in cm
dh = 0.42; %hydrauic diameter in cm made it 0.2 to meet conditions in ref.
Re = (rho_d*1000*v*10^-2*dh*10^-2)/(mu_d*10^-3);
x1_dsd = 6.92e-12;
x2_dsd = -9.95e-11;
x3_dsd = 1.51e-9;
dsd_d= x1_dsd*c0^2 + x2_dsd*c0 + x3_dsd; %given in section 3.2 in m2/s
Sc = (mu_d*10^-3)/(rho_d*1000*dsd_d);
Sh = 1.85*(Re*Sc*(dh/L))^0.33;
k_d = (Sh*dsd_d)/(dh*10^-2); %in m/s
del_d = dsd_d/k_d; %in m
ts = 100e-06; %in m
ta = 100e-09; %in m
zend = ta + ts ; %z = ta+ts
z0 = ta + ts + del_d ; %z = ta+ts+delta_d
[zdsol,cdsol]=ode23s(@(z,c) decp(z,c), [z0,zend],c0);
And the function
function dc = decp(z,c)
x1_dsd = 6.92e-12;
x2_dsd = -9.95e-11;
x3_dsd = 1.51e-9;
dsd_d= x1_dsd*c^2 + x2_dsd*c + x3_dsd;
dc = ((0.02+6*c)/dsd_d);
end

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Programming 的更多信息

标签

产品


版本

R2019b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by