Indexing into a matrix to create a plot

I would like to store Tskin for all t values and then use indexing to create a plot. How do I accomplish this?

Tambient = 20; % C
Tfilm = (T + Tambient)/2;
T = 29; 
for t = 1:1:10
    k_air_2 = 0 * (2.4131 + 0.0078 * T) * 10^-2; % W/m*C = 0 
    k_cotton = 0; % because long sleeve 
    rho_air = 1.2893 - 0.004 * Tfilm; % kg/m^3 
    mu_air = (0.0047 * Tfilm + 1.7164) * 10^-5; % kg/m*s
    k_air_ambient= (2.4131 + 0.0078 * Tfilm) * 10^-2; % W/m*C
    Re = Diameter_forearm * V * rho_air / mu_air; 
    
    h_air = (k_air_ambient/Diameter_forearm) * (0.3 + ((0.62 * Re.^.5 * Pr.^.333)/((1 + (0.4 * Pr)^.667).^.25))*(1 + ((Re/282000).^(5/8))).^.8) % J/s*K*m^2
 
    Uskin = (k_air_2/thickness_air) + (k_cotton/thickness_shirt) + (h_air) % J/s*K*m^2
    Uambient = (k_air_ambient/thickness_air) + (k_cotton/thickness_shirt) + (h_air)
    old_Tskin = T
    Tskin = [(T * Area * Cp_air * rho_air)/(t-(t-1)) + Qgen + (Uambient * Area * Tambient)]/((Area * Cp_air * rho_air / ((t-(t-1)))) + Uskin * Area);
    T = Tskin
    Tfilm = (T + Tambient)/2;
    fprintf('Your frontal forearm temperature is %.2f C after %d seconds ' ,Tskin,t)
    dT = old_Tskin - Tskin
    if dT > 0.007
        display('Your forearm probably feels cold')
    elseif dT < -0.005
        display('Your forearm probably is probably feeling hot') 
    else
        display ('Your forearm feels comfortable')
    end
end

[Ameer Hamza]

Several variables in your code are not defined. Please specify the values of all variables.

[Justin Hayes]

T = 29; % %C

% Constants

Area = .1/2; % m^2 divide by 2 for the "frontal area", I assume this is 50% of the SA of arm

Qgen = 4.5/2; %J/s divide by 2 for the "frontal area"

thickness_shirt = 0.002286; % m

thickness_air = 0.01 % m thickness of air layer in shirt

k_cotton = 0.04; % W/m*C

Diameter_forearm = 0.07; % m

Tambient = 20; % C

% Properties of ambient air

Pr = 0.71;

V = 5; %m/s

Cp_air = 1006; %J/kg*K

Tfilm = (T + Tambient)/2;

p = input('long-sleeve, short-sleeve, tank, or none: ','s')

for t = 1:1:100

k_air_2 = 0 * (2.4131 + 0.0078 * T) * 10^-2; % W/m*C = 0

k_cotton = 0;

rho_air = 1.2893 - 0.004 * Tfilm; % kg/m^3

mu_air = (0.0047 * Tfilm + 1.7164) * 10^-5; % kg/m*s

k_air_ambient= (2.4131 + 0.0078 * Tfilm) * 10^-2; % W/m*C

Re = Diameter_forearm * V * rho_air / mu_air;

h_air = (k_air_ambient/Diameter_forearm) .* (0.3 + ((0.62 * Re.^.5 * Pr.^.333)/((1 + (0.4 * Pr).^.667).^.25)).*(1 + ((Re/282000).^(5/8))).^.8) % J/s*K*m^2

Uskin = (k_air_2/thickness_air) + (k_cotton/thickness_shirt) + (h_air) % J/s*K*m^2

Uambient = (k_air_ambient/thickness_air) + (k_cotton/thickness_shirt) + (h_air)

Tskin = [(T * Area * Cp_air * rho_air)/(t-(t-1)) + Qgen + (Uambient * Area * Tambient)]/((Area * Cp_air * rho_air / ((t-(t-1)))) + Uskin * Area);

T = Tskin

Tfilm = (T + Tambient)/2

end

Answer 1

[MaryD]

you can just try

T_skin(t)= [(T * Area * Cp_air * rho_air)/(t-(t-1)) + Qgen + (Uambient * Area * Tambient)]/((Area * Cp_air * rho_air / ((t-(t-1)))) + Uskin * Area);

inside the loop.

then outside the loop

t=1:1:10

plot(t,T_skin)

[Justin Hayes]

When I use this method to plot it produces an empty plot