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Ann [662]
4 years ago
7

A flow field is characterized by the stream function ψ= 3x2y−y3. Demonstrate thatthe flow field represents a two-dimensional inc

ompressible flow. Show that the magnitude ofthe velocity at a point depends only on the distance from the origin of the coordinates.
Plot the strim ψ = 2.

Engineering
1 answer:
boyakko [2]4 years ago
8 0

Answer:

δu/δx+δu/δy = 6x-6x =0

9r^2

Explanation:

The flow is obviously two-dimensional, since the stream function depends only on the x and y coordinate. We can find the x and y velocity components by using the following relations:  

u =δψ/δy = 3x^2-3y^2

v =-δψ/δx = -6xy

Now, since:  

δu/δx+δu/δy = 6x-6x =0

we conclude that this flow satisfies the continuity equation for a 2D incompressible flow. Therefore, the flow is indeed a two-dimensional incompressible one.  

The magnitude of velocity is given by:  

|V| = u^2+v^2

    =(3x^2-3y^2)^2+(-6xy)^2

    =9x^4+18x^2y^2+9y^2

    =(3x^2+3y^2)^2

    =9r^2

where r is the distance from the origin of the coordinates, and we have used that r^2 = x^2 + y^2.  

The streamline ψ = 2 is given by the following equation:  

3x^2y — y^3 = 2,

which is most easily plotted by solving it for x:  

x =±√2-y^3/y

Plot of the streamline is given in the graph below.  

Explanation for the plot: the two x(y) functions (with minus and plus signs) given in the equation above were plotted as functions of y, after which the graph was rotated to obtain a standard coordinate diagram. The "+" and "-" parts are given in different colors, but keep in mind that these are actually "parts" of the same streamline.  

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Vehicles begin arriving at an amusement park 1 hour before the park opens, at a rale of four vehicles per minute. The gale to th
Alina [70]

Answer:

a) ≈ 30 mins

b) 8 vpm

Explanation:

<u>a) Determine how long after the first vehicle arrival will the queue dissipate</u>

The time after the arrival of the first vehicle for the queue to dissipate

= 29.9 mins ≈ 30 mins

<u>b) Determine the average service rate at the parking lot gate </u>

U = A / t

where : A = 240 vehicles , t = 30

U = 240 / 30 = 8 Vpm

attached below is a detailed solution of the given problems above

3 0
3 years ago
A soil has the following Green-Ampt parameters Effective porosity 0.400 Initial volumetric moisture content-15% Hydraulic Conduc
Rudik [331]

Answer:

The graphs are attached below

Explanation:

Ans) We know,

F(t) = K(t - to) + zΔ∅ ln[(1 + F(t)/zΔ∅]

where K = hydraulic conductivity =0.1 cm/hr

z = capillary suction =20cm

 Δ∅ = ∅ (1 - Se)

 ∅ = effective porosity , Se = initial moisture content

 Δ∅ = 0.40(1 - 0.15)

Δ∅ = 0.34

Now, F(t) = 0.1(t - to) + 20(0.34) ln[ 1 + F(t)/6.8]

F(t) = 0.1(t - to) + 6.8 ln [1+ 0.147 F(t)]

Also, infiltration rate (f),

f = K [(zΔ∅ + F)/F]

f = 0.40 [6.8 + F]/F

Condition of ponding,

Ponding time tp = K zΔ∅ i(i-k)

where, i = rainfall rate (1cm/hr)

tp = 0.40(6.8) / 0.60

tp= 4.53 hours

Now, cumulative infiltraton at ponding Fp = i tp

Fp = 1 x 4.53 or 4.53 cm

For infiltration at time less then ponding time , infiltration rate = rainfall rate

For t = 0.25 hr , f = 1cm/hr ; F = 0.25 x 1 = 0.25 cm

For t = 0.50 hr , f = 1cm/hr ; F = 0.50 cm

For t = 0.75 hr , f = 1cm/hr ; F = 0.75 cm

For t = 1 hr , f = 1cm/hr ; F = 1cm/hr

For t > tp ,

Equivalent time origin(to),

to = tp - 1/K [ Fp - z Δ∅ ln (1+ Fp/zΔ∅)

to = 4.53 - 1/0.40[ 4.53 - 6.8 ln(1 + 0.66)

to = 4.53 - 2.5 ( 4.53 - 3.44)

to = 1.82 hr

Hence,

F = 0.10( t - 1.82) + 6.8 ln[ 1+ 0.147F(t)]

Solving above equation for t by assuming F, and further solving equation for infiltration rate

Ans (a) Following is required curve :

O.S 1-5 2 time Chr)ホー Lt 2 time Chr)

Ans (c) Following is required table :

Ans (d) For time step t = 0.25 hrs

At t < tp ; i = f = 1 cm/hr

F = i x t

F = 1 x 0.25

F = 0.25 cm  

 

5 0
4 years ago
Read Shakespeare's "Sonnet 100.”
liraira [26]

Answer: quatrain

Explanation:

Reading the Shakespeare's "Sonnet 100", we can infer that the underlined section is referred to as a quatrain.

The quatrain simply refers to a type of stanza that is made up of four lines. For example, based on the information given, we can deduce that the rhyme scheme for the second quatrain is given as cdcd.

7 0
3 years ago
An estimated 60% of annual precipitation in a watershed (drainage area = 20000 acres) is evaporated. If the average annual river
Nastasia [14]

Answer:

The answer is 2.715 In

Explanation:

An estimated 60% of annual precipitation in a watershed (drainage area = 20000 acres) is evaporated. If the average annual river flow at the outlet of the basin has been observed to be 2.5 cfs, determine the annual precipitation (inches) in the basin

The annual precipitation in inches in the basin is 2.715 inches.

The solution and steps is explained in the attachment.

I hope i have been able to help.

3 0
3 years ago
A hollow, spherical shell with mass 2.00kg rolls without slipping down a slope angled at 38.0?.
mezya [45]

Answer:

\mu = 0.31

Explanation:

Given data:

mass = 2.00 kg

slope angle = 38.0

From figure

balancing force

mgsin\theta - f = ma   .....1

Balancing torque

F_R = \frac{2}{3} mR^2 \alpha ......2

for pure rolling

\alpha  = \frac{a}{R}

F = \frac{2}{3} ma

from 1 and 2nd equation

mgsin\theta - \frac{2}{3}ma =  ma

mgsin\theta = \frac{5}{3} ma

a = \frac{3}{5} g sin\theta

 = \frac{3\theta 9.8 sin 38}{5} = 3.62 m/s^2

F =\mu N

   = \frac{2}{3} ma

   = \frac{2}{3} 2\times 3.62 = 4.83 N

N =normal force =  mgsin\theta = 2 \times 9.8 sin 38 = 15.44 N

\mu \times 15.44 = 4.83

solving for  coefficent of friction we get

\mu = 0.31

4 0
3 years ago
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