HI,

I am relatively new to Fluent and bit confused over the reference values setting. As I followed the examples, sometimes they are considering projected area( ex:cylinder) normal to the flow and in some cases length of the object(ex: aerofoil). Could some one explain me the proper area to be selected?

Thanks, Shivakanth.

it really simple,

for example if you have to calculate the drag coefficient for a geometry, like flow passing a cylinder, in this case you have to specify its bases area for its reference area, if you remember the formula of drag coefficient, there is an area term present and this area term is taken as reference area in fluent.

same with length, when u have to calculate moment coefficient you have to specify it !!

hope u understand !!

Hi Syed... Thanks. Just for confirmation, if a take a plate bent in the form of an arc, the arc length would be reference area(unit depth) and reference length right?

Thanks, Shivakanth.

dear, when ever u generate a report, always mention your reference condition becasue for certain gemotries like a sphere, it is understood to take its projected area as reference area, so therefore i advise u only to take standard refernce for an analysis,else where ever mention.

the question of reference parameters are stickly concerned with the geometry and type of problem, therefore do mention your reference condition in your report so other could understand it.

for fun, just take a problem concerning flow over a cylinder form any fluid mechanics book, solve it both analyticaly and computationally then u will have an idea of reference parameter

Hey Syed...

Thanx.. as u said, let me do some homework and get back to you.

[hassan79]

hi sir

could u plz told me about refence value i wana calclate surface nuselt no in expansion pipe( diffrent diameter ) with down strean what should i used for :
temprature
lenghth
area
height
velocity
;;;;;;;




thank u

[kamran651]

Bro, it entirely depends on your problem..what you have taken temperature, length, and depth..

[sajid]

i want to calculate area of circles which would be used in ansys fluent ....
it is 2d heat exchanger and i have problem how to calculate area of circle in front of flow or which area i have to put in reference value ..
i have confusion whether i have to use area of 2 or 4 circles ???
kindly tell me how to calculate this area or which area i have to put in reference value ??? i have attached the jpeg. file of structure to further explain it ?
waiting for answer...i will be very thankful to you.
what Reference values should I used in fluent to find the area as defaults values are 1 for area,depth and length.
Area=?
Depth=?

[arif1729]

hey guys. i m new at cfd.i want to find the lift and drag,moment coefficint of an aircraft.but in case of reference value i have some problem.what should be the reference values for this.and what is this 'compute from'.
plz guys if anyone has any solution help me.

[bia]

i have the same problem and really fed up
my geometry is : the computatinal box 400mm* 750 mm the diameter of the cylinder is D=15mm. Re =150 .velocity inlet = 0.1460735 .
the problem is how to set the reference values : when i set reference area = Pi*D (seen as a lateral area ) depth =1 and length = Pi *D/2
i found the average of drag coefficient 0.45 less than 1.34 (value found in litterature ) so i change length to 1 and depth to 3 (3 = 1.34/ 0.45 ) i found values recommended but why 3 ????????????????????

[Oula]

Hello every one, I am working on simulating 2-D flow passing a circular cylinder. I got a problem with the reports> projected areas, it is not available on the screen and I can't get the parameters that I need which is the projected surface area. Can anyone help me with that?

Many Thanks
Oula

[ama294]

In the help manual it says

sets the reference area, which is used to compute the force and moment coefficients.

sets the reference length, which is used in the computation of the moment coefficient.

I think that is mean

Area = wing/cylinder area (chord*span/ diameter*height), and length = cylinder diameter/ wing chord.

[Rana shaharyar]

how to take reference length and area for d wing