| 1. |
|
|
| 2. |
|
|
| 3. |
- Larsson, Rolf
(författare)
-
Coriolis generated secondary currents and their effects on turbulent channel flow
- 1986
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The influence of secondary currents on various hydrodynamic processes in channel flow is discussed. Different mechanisms that generate secondary currents are presented. The effect of the earth's rotation on channel flow is analysed and it is shown that in wide channels and for moderate Rossby numbers the relative magnitude of the horizontal secondary currents is approximately 4 times the inverse of the Rossby number. The effect of the channel width on the magnitude of the secondary currents is shown to be small for normal aspect ratios. The Coriolis generated secondary currents are shown to develop in 30-60 channel depths downstream from zero cross-stream velocities. The effect of secondary currents on friction losses is shown to be small for secondary velocities of the order of I % of the downstream velocity. However, secondary velocities of this magnitude are shown to have significant effect on the lateral mixing of a passive tracer in a channel. The distance needed for complete lateral mixing is clearly reduced with secondary currents. This effect is shown to increase when the source is located off the centre line of the channel. It is further shown that a diffusion model for the lateral mixing is not appropriate when the secondary currents are important.
|
|
| 4. |
- Larsson, Rolf
(författare)
-
Coriolis generated secondary currents in channels
- 1986
-
Ingår i: Journal of Hydraulic Engineering. - 0733-9429 .- 1943-7900. ; 112:8, s. 750-767
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of rotation on turbulent channel flow are discussed, particularly the influence of the earth 's rotation is analyzed and some of previous literature is reviewed. It is shown that Coriolis-induced secondary currents should be of importance if they have a magnitude of 1% of the downstream velocity. A simplified analysis is used to estimate the relative magnitude of the horizontal secondary velocity at the cross-plane center point for fully-developed flow in a wide channel as a function of Rossby number. Numerical model simulations are used to investigate the influence of the side walls and the magnitude of the secondary velocities for developing flow. The results show that the secondary velocities amount to about 1% of the downstream velocity for rather slowly flowing deep channels
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
