BI-STABLE STATES IN THE WAKE OF A FINITE-WIDTH DOUBLE BACKWARD FACING STEP

• The flow past a generic ship model is investigated numerically using well-resolved large eddy simulations at Re = 8 × 10 4 . The geometric configuration at the rear of the model is analogous to a double backward facing step, and it permits the occurrence of bi-stable flow states on each step; with an asymmetrical flow topology being observed in each of the flow states across the longitudinal midplane. The mean flow topology on the top step was observed to be anti-symmetrical to the flow topology on the bottom step, and the two flow states are anti-symmetrical to each other. By introducing a base cavity on the top step, the asymmetrical flow is suppressed on both the steps; leading to the elongation of the re-circulation bubble on each step, and a reduction in the drag coefficient. The wake behind the model is analysed, and occurrence of asymmetrical flow is attributed to the difference in the strength of the streamwise vortices along the lateral edges of the top step.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Rymd- och flygteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Aerospace Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Naturresursteknik -- Havs- och vattendragsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Engineering -- Ocean and River Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)

Nyckelord

Wakes

flow control

bi-stability

backward facing step

Publikations- och innehållstyp

kon (ämneskategori)

vet (ämneskategori)