1. LECTURE NOTES 05/07 STKM3212: FOOD PROCESSING TECHNOLOGY FLUIDS MECHANIC: VISCOSITY OF FLUIDS (MEKANIK BENDALIR: KELIKATAN BENDALIR) SAIFUL IRWAN ZUBAIRI PMIFT, Grad B.E.M. B. Eng. (Chemical-Bioprocess) (Hons.), UTM M. Eng. (Bioprocess), UTM ROOM NO.: 2166, CHEMISTRY BUILDING, TEL. (OFF.): 03-89215828, FOOD SCIENCE PROGRAMME, CENTRE OF CHEMICAL SCIENCES AND FOOD TECHNOLOGY, UKM BANGI, SELANGOR

14. CONTINUE: (A) (B) (C) SLOPE: (A) > (B) > (C) = APPARENT VISCOSITY (  app ) ----   app with  SHEAR RATE (  ) (n > 1.0) (n < 1.0) (n = 1.0)

19. CONTINUE:

20. CONTINUE: Rotational Type Viscometer: Mixer (pengacau)

25. EXAMPLE 1 (NEWTONIAN): Rotational Type Viscometer Concentric cylinder (Wide-gap rotational viscometer with spindle): A wide-gap rotational viscometer with a spring constant of 7,187 dynes.cm are used to measure a viscosity (cps; %) of RO-H 2 O. The outer radius (R c ), spindle radius (R b ), and height (L) of the cylindrical spindle are 2.75 cm, 1.50 cm and 5.0 cm respectively. Determine the viscosity (  ) in N.s/m 2 of RO-H 2 O. Measurement values are given below: Spindle speed (N) Device reading; cps (% scale) 20 rpm 16 50 rpm 22 100 rpm 45

26. CONTINUE: Spindle cylinder Test fluid - RO-H 2 O Beaker “ Wide-gap rotational viscometer with spindle cylinder” L R c R b

29. CONTINUE:  You should get a LINEAR EQUATION WITH ‘0’ INTERCEPT The equation: y = 0.16x ----- so; the SLOPE = viscosity (  ) in N.s/m 2  Viscosity (  ) of RO-H 2 O = 0.16 N.s/m 2

35. CONTINUE: Spindle cylinder Test fluid - Tomato sauce Beaker “ Wide-gap rotational viscometer with spindle cylinder” L R c R b

42. CONTINUE: “ The was no mixing in any parts of the tube and the fluid flowed in straight parallel lines”  LAMINAR/VISCOUS FLOW “ As the velocity increased, it was found that a definite velocity the thread of dye became dispersed and the pattern was very erratic/inconsistent”  TURBULENT/CRITICAL VELOCITY

44. EXAMPLE 1:

45. CONTINUE: