FSalt free cheddar cheese in wheel shape is dipped into the brine solution

containing $20\%$ salt during the salting process where salt diffuses in the cheese. Cheese

has a diameter of $12cm$ and a thickness of $5cm.$ The diffusivity of salt in the cheese is

$0\mathrm{.}33{10}^{-9}\frac{m^2}{s}.$ If convective mass transfer coefficient of the system is given as $2{10}^{-7}$

$\frac{m}{s},$ determine the leading transport direction and calculate the required processing

time to obtain $12\mathrm{.}8\%$ salt concentration at the center of the cheddar cheese.