--> //initializations

--> L=18 //cm (length)
 L  = 

   18.


--> a=1.0 //cm^2 (sectional area of the stand pipe)
 a  = 

   1.


--> t=20 //min (duration in head fell)
 t  = 

   20.


--> h1=1 //m (initial head)
 h1  = 

   1.


--> h2=0.4 //m (final head)
 h2  = 

   0.4


--> d=4 //m (diameter)
 d  = 

   4.


--> //calculations

--> T=20*60 //(time in sec)
 T  = 

   1200.


--> A=(%pi*(d^2))/4 //(area)
 A  = 

   12.566371


--> k=(a*L*log(h1/h2))/(A*T) //(coefficient of permeability)
 k  = 

   0.0010937


--> //results

--> printf('coefficient of permeability=%f',k) //cm/sec
coefficient of permeability=0.001094

