NUMERICAL STUDY OF EFFECTS OF PULSATILE AMPLITUDE ON UNSTEADY LAMINARFLOWS IN RIGID PIPE WITH RING-TYPE CONSTRICTIONS

The effects of pulsatile amplitude on sinusoidal laminar flows through a rigid pipe with sharp-edged ring-type constrictions have been studi ed numerically. The parameters considered are: mean Reynolds number (R e) of the order of 100; Strouhal number (St) in the range 0.0-3.98; Wo mersley number (Nw) in the range 0.0-50.0. The pulsatile amplitude (A) varies in the range 0.0-2.0. The flow characteristics were studied th rough the pulsatile contours of streamline, vorticity, shear stress an d isobars. Within a pulsatile cycle the relations between instantaneou s flow rate (Q) and instantaneous pressure gradient (dp/dz) are observ ed to be elliptic. The relations between instantaneous flow rate (Q) a nd pressure loss (P-loss) are quadratic. Linear relations exist betwee n instantaneous flow rate (Q) and maximum velocity, maximum vorticity and maximum shear stress.