Q7) For most common class of fluids, the shear stress can be related to strain rate by What is the value of for shear-thickening (Dilatant), Newtonian, and shear-thinning (or “n” pseudoplastic). n > 1 , n = 1 , and n < 1 n <1 , n = 1 , and n >1 n > 1 , n = 0 , and n < 1 n > 2 , n = 2 , and n < 2 SOLUTION –(a) They do not begin to flow until a finite stress has been applied. BINGHAM PLASTIC – - Their resistant to flow increases with increase in SHEAR-THICKENING (DILATANT) strain rate. They follow the linear law for viscosity ie. Shear stress is NEWTONIAN – Newton’s proportional to shear strain rate. - Their resistant to flow decreases with SHEAR-THINNING (OR PSEUDOPLASTIC) increase in strain rate [It all comes out of the bottle at once!]. Some examples are, Paint is a shear-thinning fluid, as it is thick when poured, but has to be thin when brushed at a high strain rate. Toothpaste is a plastic as it begin to flow until a finite stress has been applied. doesn’t Illustrates difference between streamlines, streaklines, and pathlines Q8) The shows the superposition of paths followed by liquid jet flowing out of a figure 4 punctured tank at different instants of time. Identify the representation of the streamline, path-line (of a particle originated from hole in tank), and (of the particles that passed through the hole in the tank during the time streakline period from the first instant to the last) at the last instant.
Q7) For most common class of fluids, the shear stress can be related to strain rate by What is the value of “n” for shear-thickening (Dilatant), Newtonian, and shear-thinning (or pseudoplastic). n > 1 , n = 1 , and n < 1 n <1 , n = 1 , and n >1 n > 1 , n = 0 , and n < 1 n > 2 , n = 2 , and n < 2 SOLUTION –(a) BINGHAM PLASTIC – They do not begin to flow until a finite stress has been applied. SHEAR-THICKENING (DILATANT) - Their resistant to flow increases with increase in strain rate. NEWTONIAN – They follow the Newton’s linear law for viscosity ie. Shear stress is proportional to shear strain rate. SHEAR-THINNING (OR PSEUDOPLASTIC) - Their resistant to flow decreases with increase in strain rate [It all comes out of the bottle at once!]. Some examples are, Paint is a shear-thinning fluid, as it is thick when poured, but has to be thin when brushed at a high strain rate. Toothpaste is a plastic as it doesn’t begin to flow until a finite stress has been applied. Illustrates difference between streamlines, streaklines, and pathlines Q8) The figure 4 shows the superposition of paths followed by liquid jet flowing out of a punctured tank at different instants of time. Identify the representation of the streamline, path-line (of a particle originated from hole in tank), and streakline (of the particles that passed through the hole in the tank during the time period from the first instant to the last) at the last instant.