[mik_urb]

Hi everyone,
i'm trying to detemine discharge coefficient for simple problem - outflow of water from the large tank through small orifice.
After few trials i am getting Cd=0.8. Cd=Qflow3D/Qtheoretical

Any tips or suggestions ?

[MSM1985]

For finding out discharge coeffcient from model data, same orifice equation will work

Qmodel = Cd x A x sqrt(2gh)

Qflow3D/Qtheoretical works when Qtheoretical is determined without Cd.

[mik_urb]

Hi, thanks for reply.

I dont think i described the problem in detail.

I am trying to calculate Cd from equation Cd=Q_flow3D/(Asqrt(2gh)).
(in my mind A x sqrt(2gh) = Qtheoretical )
To get Q_flow3D and A(area) i am placing baffle (flux surface) in orifice.
To get h i am placing history probe.
BC Ymin,Ymax,Zmin -wall; Xmin-fluid elevation, Xmax-outflow, Zmax- fluid fraction 0


After that train of thought i am getting Cd around 0.8, i was hoping for 0,6-0,65.

[MSM1985]

Cd varies from 0.61 - 0.98, depending upon orifice entrance conditions

[krunker]

How to accurately determine Cd value.

basketball stars

[MSM1985]

most accurate method is physical model observations

[vekibix]

The discharge coefficient is a dimensionless parameter used in fluid dynamics to describe the efficiency of a fluid flow through a constriction or an orifice. It represents the ratio of the actual flow rate to the theoretical maximum flow rate under the same conditions.