The hypothesis is that the upper
rolls need more room to developp, so we mqde a higher mesh.
/*user define function*/
/* udf pour viscosite*/
else if (temp<300.75)
Initial Velocity, |v|=1, delta T=1
If we simulate this case without
any viscosity gradient, the convergence is to 2 rolls, one above the other.
We can notice the developpement
of the lower roll and the motion of the fluid above, but still not one
Velocity, |v|=10, delta T=1
Even with a greater velocity initialisation, the convergence is similar to the last one.
Velocity, |v|=10, delta T=10
The solution could have been to take a bigger Rayleigh number, but , as we can see, the researched case is unstable and with a greater Rayleigh, the case converges to one single roll.
Velocity, |v|=1, delta T=5
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