Patent ID: 8874374

Claim:
A method for determining a rate of turbulent kinetic energy dissipation (TKED) in a turbulent fluid environment, the method comprising: providing a light source a first end of a predetermined path-length (L), for passing at least one beam of light through the turbulent fluid environment; using an angle of arrival detection unit for detecting an angle of arrival of the at least one beam of light wherein the angle of arrival detection unit includes a single lenslet; and by using at least one processor: obtaining an autocorrelation of an angle of arrival of light φ 2 (d) passing through the turbulent fluid environment and along a predetermined path-length (L), by using the equation: φ 2 ⁡ ( d ) = 2 ⁢ ⁢ π ⁢ ⁢ ∫ 0 2 ⁢ π ⁢ ⁢ ⅆ θ · sin ⁢ ⁢ θ · VSF ⁡ ( θ ) · g φ ⁡ ( θ ) · J 0 ( 2 ⁢ π λ ⁢ ⅆ sin ⁡ ( θ ) ) wherein θ is an angle of arrival of the light, VSF(θ) is a volume scattering function obtained as a function of a time series of a scattering angle of light and g φ (θ) is an universal fudge function obtained by using historical turbulence measurement data, J 0 is a Bessel function of the first kind, λ is a wavelength of light and d is an independent variable of the equation describing a relationship between the angle of arrival of light and the volume scattering function; and calculating a temperature spectra E θ (k) as a function of the Fourier transform of the angle of arrival of light φ 2 (d) by using the equation: E θ ⁡ ( k ) = - ⁢ 2 π ⁢ ⁢ L ⁢ ∫ k ∞ ⁢ k 1 ⁢ ⅆ ⅆ k 1 ⁢ ( ϕ ⁡ ( k 1 ) k 1 ) k 1 2 - k 2 ⁢ ⁢ ⅆ k 1 wherein Φ(k 1 ) is a Fourier transform of the autocorrelation of the angle of arrival of light—k is a wavenumber, and k 1 is a variable wavenumber, and wherein the peak of the temperature dissipation spectra represents the rate of TKED.