cases:case006

# Square-Section Duct 180 Degree Bend

Turbulent flow in a square cross-section duct made of a 180o bend and two long straight inlet and outlet parts. 3D flow with constant temperature.

#### Geometry of the Computational Domain

180o bend section connected to straight inlet and outlet tangents, all of square section: $D \times D = 88.9 \times 88.9$ mm. Centreline curvature radius of the bend: $R_c = 3.357D$ (see figure 1).

In the experiment the inlet section consisted of a straight duct of around $30D$ length, with the flow reported to be close to fully developed on approaching the bend section.

Fig. 1: Duct bend geometry and coordinate system

#### Flow Parameters

Air at standard conditions.

• Inlet bulk axial velocity $W_B = 11$ m/s.
• Reynolds number based on the bulk axial velocity $W_B$: $Re = W_B D/\nu = 56,690$.

#### Inflow Conditions

Measurements/simulation data corresponding to a fully-developed turbulent duct flow are provided in file inlet-data.dat, consisting of contour maps of:

• First order moments: $U$, $V$, $W$
• Turbulent kinetic energy, $k$ and dissipation rate, $\varepsilon$

If using these it is suggested to apply them at least $1D$ upstream of the bend inlet.

Velocity measurements using a rotatable hot-wire probe.

#### Measurement Errors

Analyzed but no published values.

Contour maps are provided at 5 different angular positions ($\Psi = 0^o$, $45^o$, $90^o$, $135^o$, $180^o$) of:

• First order moments: $U/W_B$, $V/W_B$, $W/W_B$
• Second order moments: $u'/W_B$, $v'/W_B$, $w'/W_B$, $\overline{uv}/W_B^2$, $\overline{uw}/W_B^2$, $\overline{vw}/W_B^2$

Sample plots of selected quantities are available.

The data can be downloaded as compressed archive files from the links below, or as individual files by selecting those required from the tables.

Mean velocities file Second Moments
$\Psi=0^o$ sqd-vel-000.dat sqd-rss-000.dat
$\Psi=45^o$ sqd-vel-045.dat sqd-rss-045.dat
$\Psi=90^o$ sqd-vel-090.dat sqd-rss-090.dat
$\Psi=135^o$ sqd-vel-135.dat sqd-rss-135.dat
$\Psi=180^o$ sqd-vel-180.dat sqd-rss-180.dat
1. Choi, Y.D., Moon C., Yang, S.H. (1990). Measurement of turbulent flow characteristics of square duct with a 180 degree bend by hot wire anemometer. Proc. Int. Symp. on Engineering Turbulence Modelling and Measurement, Dubrovnik.
2. Chang, S.M., Humphrey, J.A.C., Modavi, A. (1983). Turbulent flow in a strongly curved U-bend and downstrean tangent of square cross sections. Physico-Chemical Hydrodynamics, Vol. 4, pp. 243-269.
3. Choi, Y.D., Iacovides, H., Launder, B.E. (1989). Numerical computation of turbulent flow in a square-sectioned 180 deg bend. J. Fluids Engg. Vol. 111, pp. 59-68.
4. Sotiropoulos, F., Patel, V.C. (1993). Evaluation of some near-wall models for the Reynolds-stress transport equations in a complex 3-d shear flow. Near wall turbulent flows, pp. 987.

Indexed data:

case006 (dbcase, confined_flow)
case006
titleSquare-Sectioned Duct 180 degree Bend
authorChoi, Moon, Yang
year1990
typeEXP
flow_tag3d, curvature, constant_cross_section