GATE-CH-1993-9-c-fm-2mark

Match the following: The shear stress vs. velocity gradient characteristics are shown in figure.

• I.

• Answer 1C. Bingham plasticB. DilatantD. Pseudo plasticA. Newtonian

• II.

• Answer 2C. Bingham plasticB. DilatantD. Pseudo plasticA. Newtonian

• III.

• Answer 3C. Bingham plasticB. DilatantD. Pseudo plasticA. Newtonian

• IV.

• Answer 4C. Bingham plasticB. DilatantD. Pseudo plasticA. Newtonian

GATE-CH-1988-2-ii-fm-1mark

For pseudoplastic fluids, increase in shear rate

• increases the apparent viscosity

• decreases the apparent viscosity

• has no effect on apparent viscosity

• has unspecified effect

GATE-CH-1989-2-i-c-fm-1mark

For a dilatant fluid, the magnitude of the slope of the shear stress versus the velocity gradient curve 末末- with increasing velocity gradient.

• increases

• decreases

• remains unchanged

• may decrease or increase

GATE-CH-1994-1-j-fm-1mark

The shear stress穆hear rate relationship for a liquid whose apparent viscosity decreases with increasing shear rate is given by

• ¥(¥displaystyle ¥tau _{yx} = -m¥left [¥frac {dv_x}{dy}¥right ]^{n-1}¥frac {dv_x}{dy}¥) for ¥(n <1¥)

• ¥(¥displaystyle ¥tau _{yx} = -m¥left [¥frac {dv_x}{dy}¥right ]^{n}¥) for ¥(n =1¥)

• ¥(¥displaystyle ¥tau _{yx} = -m¥left [¥frac {dv_x}{dy}¥right ]^{n-1}¥frac {dv_x}{dy}¥) for ¥(n >1¥)

• ¥(¥displaystyle ¥tau _{yx} = -m¥frac {dv_x}{dy} + ¥tau _o¥)

GATE-CH-2001-2-6-fm-2mark

A Bingham fluid of viscosity ¥(¥mu ¥) = 10 Pa.s, and yield stress ¥(¥tau _o¥) = 10 kPa, is sheared between flat parallel plates separated by a distance 10¥(^{-3}¥) m. The top plate is moving with a velocity of 1 m/s. The shear stress on the plate is

• 10 kPa

• 20 kPa

• 30 kPa

• 40 kPa

GATE-CH-2003-10-fm-1mark

A lubricant 100 times more viscous than water would have a viscosity (in Pa.s)

• 0.01

• 0.1

• 1

• 10

GATE-CH-2004-49-fm-2mark

Viscosity of water at 40^oC lies in the range of

• ¥(1¥times 10^{-3}¥) - ¥(2¥times 10^{-3}¥) kg/(m.s)

• ¥(0.5 ¥times 10^{-3}¥) - ¥(1 ¥times 10^{-3}¥) kg/(m.s)

• 1 - 2 kg/(m.s)

• 0.5 - 1 kg/(m.s)

GATE-CH-2005-12-fm-1mark

Match the following types of fluid (in group I) with their respective constitutive relations (in group II), where ¥(¥tau ¥) is the stress and ¥(¥dot {¥gamma }¥) is the strain rate.

Group I	Group II
(P) Pseudoplastic	(I) ¥(¥tau = ¥mu ¥dot {¥gamma }¥)
(Q) Bingham plastic	(II) ¥(¥tau = ¥tau _o + K¥dot {¥gamma }¥)
	(III) ¥(¥tau = K|¥dot {¥gamma }|^n; ¥quad n < 1¥)
	(IV) ¥(¥tau = K|¥dot {¥gamma }|^n; ¥quad n > 1¥)

• P-I, Q-IV

• P-IV, Q-I

• P-II, Q-III

• P-III, Q-II

GATE-CH-2006-38-fm-2mark

A fluid obeying the constitutive equation ¥[ ¥tau = ¥tau _o + K ¥left (¥frac {dv_x}{dy}¥right )^{¥frac {1}{2}}, ¥quad ¥tau > ¥tau _o ¥] is held between two parallel plates a distance ¥(d¥) apart. If the stress applied to the top plate is ¥(3¥tau _o¥), then the velocity with which the top plate moves relative to the bottom plate would be

• ¥(¥displaystyle 2 ¥left (¥frac {¥tau _o}{K}¥right )^2d¥)

• ¥(¥displaystyle 3 ¥left (¥frac {¥tau _o}{K}¥right )^2d¥)

• ¥(¥displaystyle 4 ¥left (¥frac {¥tau _o}{K}¥right )^2d¥)

• ¥(¥displaystyle 9 ¥left (¥frac {¥tau _o}{K}¥right )^2d¥)

GATE-CH-2013-10-fm-1mark

The apparent viscosity of a fluid is given by ¥(0.007 ¥left (¥dfrac {dV}{dy}¥right )^{0.3}¥) where ¥(¥left (¥dfrac {dV}{dy}¥right )¥) is the velocity gradient. The fluid is

• Bingham plastic

• dilatant

• pseudoplastic

• thixotropic

GATE-CH-2014-13-fm-1mark

Which of the following statements are CORRECT?

• [P.] For a rheopectic fluid, the apparent viscosity increases with time under a constant applied shear stress
• [Q.] For a pseudoplastic fluid, the apparent viscosity decreases with time under a constant applied shear stress
• [R.] For a Bingham plastic, the apparent viscosity increases exponentially with the deformation rate
• [S.] For a dilatant fluid, the apparent viscosity increases with increasing deformation rate

• P and Q only

• Q and R only

• R and S only

• P and S only

GATE-XE-2012-B-14-fm-2mark

The figure given below shows typical non-dimensional velocity profiles for fully developed laminar flow between two infinitely long parallel plates separated by a distance ¥(a¥) along ¥(y¥)-direction. The upper plate is moving with a constant velocity ¥(U¥) in the ¥(x¥)-direction and the lower plate is stationary.

Match the non-dimensional velocity profiles in column I with the pressure gradients in column II.

Column I	Column II
P. profile I	1. ¥(¥dfrac {¥partial P}{¥partial x} > 0¥)
Q. profile II	2. ¥(¥dfrac {¥partial P}{¥partial x} < 0¥)
R. profile III	3. ¥(¥dfrac {¥partial P}{¥partial x} = 0¥)

• P-2; Q-3; R-1

• P-3; Q-2; R-1

• P-3; Q-1; R-2

• P-1; Q-2; R-3

GATE-CH-2012-52-53-fm-4mark

A Newtonian fluid of viscosity ¥(¥mu ¥) flows between two parallel plates due to the motion of the bottom plate (as shown below), which is moved with a velocity ¥(V¥). The top plate is stationary.

(i) The steady, laminar velocity profile in the ¥(x¥)-direction is

{#1}

(ii) The force per unit unit area (in the ¥(x¥)-direction) that must be exerted on the bottom plate to maintain the flow is

{#2}