Naslov
Estimation of turbulence kinetic energy dissipation rate in a Bora event

Autori
Večenaj, Željko ; Belušić, Danijel ; Grisogono, Branko

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
29th International Conference on Alpine Meteorology - Extended Abstracts / - : Météo-France, 2007, 745-748

Skup
29th International Conference on Alpine Meteorology

Mjesto i datum
Chambéry, Francuska, 04.06.2007. - 08.06.2007

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
bora wind; dissipation rate; inertial dissipation technique; structure function; local isotropy

Sažetak
During a bora event, the turbulence is strongly developed in the lee of the mountain. Wind speed at Senj was measured at 13 m above the ground with a 3D ultrasonic anemometer operating at 4 Hz sampling frequency. This data was used for evaluation of the turbulent kinetic energy (TKE) dissipation rate ε . The estimated value of ε with the inertial dissipation method (IDM) for this event is 1.22 m^2 s^-3 and is taken as the reliable one. An alternative method is based on the third-order streamwise velocity structure function (3SF) which requires a local turbulence isotropy. Using this approach a significantly lower value of ε is obtained, not surpassing 0.70 m^2 s^-3. Inspecting the stronger isotropy condition for the inertial subrange, i.e. the 4:3 ratio of vertical and transverse to streamwise velocity spectra, it is found that the present anemometer's sampling rate only approaches the inertial subrange. This partly explains the lower value of ε obtained using the second method. Thus, the anemometer of a much higher sampling frequency is needed for further studies of the bora-related small-scale turbulence.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA