written 6.2 years ago by |
Buckingham pi-Theorem states that,"If there are in variables (dependent and independent variables)in a dimension-ally homogeneous equation and if these variables contain m fundamental dimensions (M,L,T) the the variables are arranged into (n-m) dimensionless terms These dimensionless terms are called $\pi$ terms
Step1: Mathematically, if any variable x,depends on idependent variables $x_{2},x_{3},x_{4}....x_{n}$ then the functional relationship between dependent variable is expressed as
$X_{1}=f(x_{2},x_{3},x_{4}.....x_{n})$
equation can be written as
$f_{1}(x_{1},x_{2},x_{3},x_{4},.......x_{n})$=0
It is dimension-ally homogeneous equation and contains n variables.
Step 2:- The equation can be written in terms of number of dimensionless $\pi$ term which is equal to (n-m)
f$(\pi_{1},\pi_{2}...\pi-m)$=0
Step:-3 Each $\pi$ term contains m+1 variables, where m is the number of fundamental dimensions and it is also called as repeating variables
Step:-4 If $x_{2},x_{3},x_{4}$ are repeating variables then each $\pi$ is written as
$\pi_{1}=x_{2}^{a_{1}}.x_{3}^{b_{1}}.x_{4}^{c_{1}}x_{1}$
$\pi_{2}=x_{2}^{a_{2}}.x_{3}^{b_{2}}.x_{4}^{c_{2}}x_{5}$
$\pi_{n-m}=x_{1}^{a_{n-m}}.x_{2}^{b_{n-m}}.x_{3}^{c_{n-m}}x_{n-m}$
where $x_{1},x_{5.......,x_{n-m}}$are numerating variables
Step:-5 Where each equation is solved by principle of dimensional homogeneity and the values a,b,c are obtained
Step:-6 Substitute the value of a,b,c in their corresponding $\pi_{1},\pi_{2},\pi_{3}.....,$ etc. in equation
Step:-7 The value of $\pi_{1},\pi_{2},\pi_{3}$ are are substitute inequation
Step:-8 The required expression cab be obtained by expressing any one of the x-terms as a function of others