Simulation of temperature influence on flow pattern and residence time in a detention tank
Artikel i vetenskaplig tidskrift, 2006

Three-dimensional simulations were used to model how a temperature difference between the incoming water and tank water influences the flow pattern and residence time in a detention tank. Buoyant, neutrally buoyant and negatively buoyant incoming jets were simulated. The simulations were compared with measurements for neutrally buoyant jets in a large-scale model of a detention tank (13 × 9×1 m). The results show that a negatively buoyant jet gives slightly less effective volume, defined as the time when 50% of added tracer has passed the outlet divided by the nominal residence time, than a neutrally buoyant jet. The flow pattern for a negatively buoyant jet at low densimetric Froude numbers consists of a current that travels along the bottom towards the outlet and a counter current at the surface towards the inlet, while the neutrally buoyant jet excites a surface jet with two large eddies on each side of the jet. This implies that the short-circuiting will decrease when a negatively buoyant jet at low densimetric Froude number occurs in the tank. The difference between the flow pattern excited by a buoyant jet and a neutrally buoyant jet is small.

residence time

Computational fluid dynamics

negatively buoyant jet

storm water

detention tank

temperature

Författare

Åsa Adamsson

Chalmers, Bygg- och miljöteknik, Vatten Miljö Teknik

Lars Bergdahl

Chalmers, Bygg- och miljöteknik, Vatten Miljö Teknik

Nordic Hydrology

0029-1277 (ISSN)

Vol. 37 1 53-68

Ämneskategorier

Vattenteknik

DOI

10.2166/nh.2005.030