Mechanical Engineering - Hydraulics and Fluid Mechanics - Discussion

4. 

In one dimensional flow, the flow

[A]. is steady and uniform
[B]. takes place in straight line
[C]. takes place in curve
[D]. takes place in one direction

Answer: Option B

Explanation:

No answer description available for this question.

Arun said: (Jul 7, 2013)  
If the flow of fluid in one direction only, which is called one dimensional flow (i.e. mostly flows in x-direction). Option D is correct.

Badrul said: (Oct 6, 2013)  
Stream line of flow must be strieght line so answer is D.

Nanu Dayma said: (Oct 29, 2013)  
B answer because of flow of fluid is one direction so its diagram is straight pv constant.

Sabir Khan said: (Nov 7, 2013)  
It should be in a straight line, otherwise there will be two component of velocity resulting 2d flow.

Bkrish said: (Jan 1, 2014)  
For one dimensional flow, the velocity is the function of single coordinate (i.e) u= f(x).

Let u be the velocity.

The function u = f(x) is the straight line.

Therefore one dimensional flow is the straight line flow.

Manik said: (Feb 1, 2014)  
I think answer is D because one dimensional flow means heat flows in only one direction.

Waseem Iqbal said: (Apr 22, 2014)  
One dimensional means which only changes w.r.t one space coordinates means it only depends on one coordinate.

Waseem Iqbal said: (Apr 22, 2014)  
Dear @Arun you are wrong.

One dimension does not mean like only in one space coordinates direction(as you say in x).

The direction may change from x to y coordinate direction but it is single.

Deepak said: (Dec 18, 2014)  
A flow in which the streamlines of its moving particles are represent by straight line is called one dimensional flow.

Bidur said: (Dec 18, 2014)  
Answer is D because straight line does not mean that it is flowing only in one direction.

Surender said: (Mar 17, 2015)  
1 D flow takes place in one direction only. So the correct answer is D.

Zxcv said: (Apr 18, 2015)  
The single space coordinate is usually the distance measured along the center-line (not necessarily straight) in which the fluid is flowing.

Example: The flow in a pipe is considered one-dimensional when variations of pressure and velocity occur along the length of the pipe, but any variation over the cross-section is assumed negligible.

In reality, flow is never one-dimensional because viscosity causes the velocity to decrease to zero at the solid boundaries.

Kapelemera said: (Apr 23, 2015)  
It is because the motion is translation and rotational.

Rahul Kumar said: (Jul 4, 2015)  
If pressure and velocity vary in one dimensional flow then pv remained constant as it graph shows. The straight line from origin. Usually fluid flowing in a pipe considered one dimensional flow. I hope it's something which make you understand.

Rajeev said: (Jul 21, 2015)  
I think both the option B and D are correct.

Rajesh said: (Aug 25, 2015)  
Answer B & D are correct because as it indicates one dimensional flow.

Jeevaa said: (Aug 31, 2015)  
Which one is correct B or D?

Prateek said: (Sep 11, 2015)  
1-D flow doesn't necessarily mean in a straight line, so answer should be D.

Vaibhav Bhagat said: (Sep 16, 2015)  
Both B & D correct because it is straight and flow in only 1 direction either x y or z.

Radha Choudhary said: (Sep 18, 2015)  
Both Option B & D are correct because it is indicates 1 dimensional flow.

Mahesh said: (Mar 9, 2016)  
Proper answer is D because if we think as straight line by considering u=f(x), it may have two components with respect to a reference point it means it represent 2d flow. So answer is D.

Nitish said: (Jul 7, 2016)  
It is either straight or one dimensional.

Rani Kokare said: (Jul 25, 2016)  
The flow is flow in the direction of ''x'' co-ordinate. It flow contain only 'x'co-ordinate.

Djarma said: (Oct 10, 2016)  
Please tell me the correct answer.

Sandy said: (Nov 25, 2016)  
ANS IS D ONLY.

Straight line is a 2d dimension.

Er. Harshit Mangla said: (Dec 14, 2016)  
One-dimensional flow.

All the flow parameters may be expressed as functions of time and one space coordinate only.

The single space coordinate is usually the distance measured along the centre-line (not necessarily straight) in which the fluid is flowing.

Example: the flow in a pipe is considered one-dimensional when variations of pressure and velocity occur along the length of the pipe, but any variation over the cross-section is assumed negligible.

In reality, flow is never one-dimensional because viscosity causes the velocity to decrease to zero at the solid boundaries.

If however, the non-uniformity of the actual flow is not too great, valuable results may often be obtained from a "one-dimensional analysis".

The average values of the flow parameters at any given section (perpendicular to the flow) are assumed to be applied to the entire flow at that section.

Neel K said: (Mar 21, 2017)  
One dimension means there is no turbulent flow.

Sharique said: (Jun 27, 2017)  
Answer will be D.

Ashish Baranwal said: (Aug 10, 2017)  
One dimensional flow mean the flow which is in a straight line.

Answer B is correct.

Shubham Khatri said: (Aug 25, 2017)  
Both B & D are correct as if the flow is one dimensional it will flow in a straight line. As one dimension always represents a single coordinate, i.e., U=f(x) if we consider flow along the x direction. But this explanation follows option D too as if the flow is considered along line x=y then with respect to the coordinate system which is tilted by 45 degrees it is a flow along the axis and hence again in a straight line.

So the velocity will be given as U=f(x') where x' would be the x direction in transformed axis and hence flow in a single direction is also a one-dimensional flow.

Kaushik said: (Sep 21, 2017)  
Option B is not correct because flow in a straight line is called laminar flow.

Option D is correct.

Xyz said: (Oct 12, 2017)  
B, right because we considered fluid is non viscous in nature and PV graphs show straight line, PV ' constant.

Aman said: (Apr 16, 2018)  
No, the One-dimensional flow has nothing to do with the straight line or curve. If the entire flow parameter requires only 1 independent variable to completely specify the flow then it is called one dimensional.

Utkarsh Saxena said: (May 2, 2018)  
I agree @Aman.

The one-dimensional flow does not necessarily mean a straight line.

Suppose an ant is moving in a zig-zag path. If we look at the path of an ant from above we will observe ant is moving in a zig-zag path which is lying on a 2d plane but if you ask the ant what is the path of your motion? The ant will definitely say that I am is moving in a straight line. Because ant will not be able to observe its motion from above. As soon as the ant takes turns on its path its X coordinate will also take a turn with it (ant). So if you are moving in a zig-zag path you can not say that you are moving in 2d. It will be ond D only.

Utkarhs Saxena said: (May 2, 2018)  
Option D is correct. Option B is the subset of option D. Because a Straight Line path and a zig-zag path both can be one Dimension.

Hayagreeva Shreekanth Velpuri said: (Feb 14, 2019)  
A flow, in which the streamlines of its moving particles are represented by straight line, is called one-dimensional flow.

Ref: R.S KHURMI & J.K.GUPTA.

Kalyani said: (May 24, 2019)  
1-dimensional flow is when velocity is in 1 direction only.

Ref: R.K. BANSAL.

Suresh said: (Aug 28, 2019)  
@Zxcv, here the question asked from kinematics.

So we can't consider the forces acting on it.

BUT you consider sheer force. So it is wrong.

And your explanation is correct to incase of dynamics.

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