X Second Lame parameter. 



Second viscosity coefficient. 



First Lame parameter. 



\s First viscosity coefficient. 



n 3. 14159 . . . 



p Density; p Q is mean density. 



o Element of surface area. 



j .-, Total stress tensor (normal components bein§ 



tensile stresses if positive). 



i|f Phase parameter. 



Complex frequency. 

 id Real frequency (radians/sec). 



V Gradient operator. 



Standard symbol for repeated multiplication. 



Standard summation notation. 



