Moisture equation

Questions
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1

Hi,

My problem It is about the diffusive transport equation designed for a two-dimensional plane.
The physical problem consists in predicting the drying time according to the radial and tangential humidity of a 48 mm by 48 mm piece of radiata pine wood.

I need to use this equation.

I need to be able to get this same data:

The idea is to design a code in wolfram mathematica to obtain radial vs. CHO (Moisture Content) and tangential vs. CHO graphs. I’ve been using this code but I can’t get the necessary results

Ec = D[CH[x, y, t], t] == 
   Dm*(D[CH[x, y, t], x, x] + D[CH[x, y, t], y, y]);

Ecx = D[CH[x, y, t], t] == Dm*(D[CH[x, y, t], x, x]);

Ecy = D[CH[x, y, t], t] == Dm*(D[CH[x, y, t], y, y]);

M0 = 130;

a = -21.05;

b = 18.5;

Dm = Exp[a + (b*CH[x, y, t])];

ci = CH[x, y, 0] == M0;

ejes = 24;

R = {D[CH[x, y, t], x] == 0 /. x -> 0, 
   D[CH[x, y, t], y] == 0 /. y -> 0, 
   D[CH[x, y, t], x] == 0 /. x -> ejes, 
   D[CH[x, y, t], y] == 0 /. y -> ejes};

H = NDSolve[{Ec, ci, R}, CH, {t, 0, 40}, {x, 0, ejes}, {y, 0, ejes}];

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