1993-9-c-fm

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

I.

II.

III.

IV.

1988-2-ii-fm

For pseudoplastic fluids, increase in shear rate

- increases the apparent viscosity
- decreases the apparent viscosity
- has no effect on apparent viscosity
- has unspecified effect

1989-2-i-c-fm

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

- increases
- decreases
- remains unchanged
- may decrease or increase

1994-1-j-fm

The shear stress–shear 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 \(n >1\)
- \(\displaystyle \tau _{yx} = -m\frac {dv_x}{dy} + \tau _o\)

2001-2-6-fm

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

2003-10-fm

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

- 0.01
- 0.1
- 1
- 10

2004-49-fm

Viscosity of water at 40^{o}C 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)

2005-12-fm

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

2006-38-fm

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

- \(\displaystyle 2 \left (\frac {\tau _o}{K}\right )^2d\)
- \(\displaystyle 3 \left (\frac {\tau _o}{K}\right )^2d\)
- \(\displaystyle 4 \left (\frac {\tau _o}{K}\right )^2d\)
- \(\displaystyle 9 \left (\frac {\tau _o}{K}\right )^2d\)

2013-10-fm

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

2014-13-fm

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

XE-2012-B-14-fm

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

2012-52-53-fm

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}

Last Modified on: 02-May-2024

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