Fluid Mechanics Exam 1

false

A body immersed in a fluid will experience a force only if there is a relative motion between the body and the fluid.

false

A control volume has to be fixed in space with the fluid moving through it and it may not move with the fluid such that the same fluid particles are always inside it.

an infinitesimally small, a finite, or an infinitely large

A control volume is _____ region of the flow.

M < 0.3

A flow can be treated as an incompressible flow when ________________

inviscid

A flow that is assumed to involve no friction, thermal conductivity or diffusion is called ____ flow.

unsteady flow

A flow where the flow-field variables at any given point are changing with time is called _____

The non-dimensional pressure and temperature distributions are the same for both flows, The lift coefficients obtained are the same.

Consequences of two flows being dynamically similar

supersonic flow

Consider a vehicle flying through the atmosphere. If the flow over the vehicle is characterized by the presence of shock waves at the nose of the vehicle, across which the flow properties change discontinuously, as what type of flow would the freestream be classified?

Rate of work done on the fluid inside the control volume v due to the pressure force on S.

Consider the energy equation, the term - closed surface integral P V * dS represents

Net rate of flow of total energy across the control surface S.

Consider the energy equation, the term surface integral of rho(e + V^2/2) V * dS represents

Rate of work done on the fluid inside v due to body forces.

Consider the energy equation, the term volume integral of rho (f* V)dV represents

The time rate of change of momentum contained inside the control volume

Consider the momentum conservation equation, what does volume integral of rho V dv represent?

Body forces

Consider the momentum conservation equation, what does volume integral of rho f dv represent?

(2ax + by) i + bx j + c k

Consider the scalar T space equal space a x to the power of 2 space plus space b x y space plus space c z . The gradient of T is given by

- ( i + j + k )

Consider the vector field bold italic v space equal space y space bold italic i space plus space z space bold italic j space plus space x space bold italic k . The curl of bold italic v is given by

0

Consider the vector field bold italic v space equal space y space bold italic i space plus space z space bold italic j space plus space x space bold italic k . The divergence of bold italic v is given by

true

Flows at high Reynolds numbers are often studied by dividing the flow into two regions, where the influence of friction, thermal conduction and diffusion is limited to a very thin region adjacent to the surface and the remainder of the flow is treated as an inviscid flow.

pressure drag

For a blunt body, most of the drag is due to _____.

heating the body and the airflow around the body

For a body in reentry, the large kinetic and potential energy near the outer edge of the atmosphere reduces to virtually zero kinetic and potential energy as the body reaches the surface of the earth. All this energy goes into ____

continuity and momentum equations

For incompressible flow with constant viscosity, the _________ are necessary and sufficient tools to solve for the primary flow-field variables.

specific gas constant

For the perfect gas equation of state expressed as p = rho R T , R represents

hypersonic flow

For which of these flows is the temperature in the shock layer high enough for chemical reactions to occur in the air?

liquids

Hydrodynamics refers to the flow of ____

speed of sound

If Mach number is defined as M = V/a, a refers to

calorically perfect

If a gas is ________, then the internal energy satisfied the relation e space equals space c subscript v T, where cv is the specific heat at constant volume and T is the temperature.

stalled

If an airfoil is inclined at a high incidence angle to the flow, then the boundary layer will tend to separate from the top surface and a large wake is formed downstream. Such a separated flow is a characteristic of a flow-field over a ____ airfoil.

continuum flow

If the mean free path, λ is orders of magnitude smaller than the scale of the body measured by d, then the flow is called ____

true

Mass conservation - Scalar equation, Momentum conservation - Vector equation, Energy conservation - Scalar equation

Pressure - scalar, Velocity - vector, Temperature - scalar, Density - scalar

Name vector or scalar for pressure, velocity, temp. and density

steady, unsteady, viscous, inviscid, compressible and incompressible

One way of expressing the continuity equation is partial rho/ partial t + del * (rho*V) = 0 This form is valid for _____ flows.

true

Pressure coefficient is defined as

False

Reynolds number is defined as Re = mu/ rho*V*c

kg / (m^2 s)

The SI units of mass flux are ____.

absorption of radiation originating outside the system, local emission of radiation by the fluid itself, mass diffusion across the control surface

The heat transfer mechanisms to or from the fluid that can be visualized as volumetric heating of the fluid inside the control volume could be due to ________

Euler

The momentum equations for inviscid flows are called the _____ equations.

no slip

The phenomenon where friction causes the infinitesimally thin layer of air molecules immediately adjacent to the body surface to stick to the surface is called the _____ condition.

boundary layer

The thin viscous region adjacent to a body in a flow field where dissipative effects are included is called _____.

force

The time rate of change of momentum is called ____.

divergence

The time rate of change of the volume of a moving fluid element, per unit volume represents the _____ of the velocity field.

conduction

The transfer of heat from a hotter region to a colder region by random molecular motion is called thermal ______

buoyancy

The weight of fluid displaced by an object that is immersed in the fluid is equal to the force of___.

blunt

To minimize aerodynamic heating we need a _____ body

the bodies and any other solid boundaries are geometrically similar, the similarity parameters are the same

Two flows will be dynamically similar if _____.

velocity distribution

We need to measure the ______ using a Pitot rake in order to calculate the drag of a two dimensional body in a wind tunnel.

kg / m s

What are the SI units for the absolute viscosity coefficient (μ)?

N/m^2

What are the SI units of shear stress?

solid

When a force is applied tangential to the surface of a ____, it will experience a finite deformation and the shear stress will usually be proportional to the amount of the deformation.

hydrostatic equation

dp = -g rho dy