This paper presents Large Eddy Simulations of a compressible turbulent flow through a duct of square cross-section with a localized heat source on its bottom wall. The potential applications are related to the accidental heat release in a road tunnel. A constant temperature TW is imposed on all duct walls except for the spot location. Two distinct heating configurations are considered. In the f...

Laser-based missile-defence systems are being increasingly employed on aircraft to provide protection when attacked by optically-guided weapons. In some engagements the laser beam must pass through the exhaust gases of the aircraft. To predict the increase in laser beam divergence and jitter of the laser beam direction, an understanding of the exhaust gas structure and its influence is required...

In developed turbulence, the effective magnetic pressure of a large-scale field (non-turbulent plus turbulent contributions) can become negative. This is known to lead to a large-scale instability in strongly stratified turbulence that produces spontaneous magnetic flux concentrations. Previous studies using a horizontal magnetic field resulted in elongated field concentrations with a strength ...

In a statistical study of the decay of individual sunspots based on DPR data we find that the mean instantaneous area decay rate is related to the spot radius r and the maximal radius r0 as D = CD r/r0, CD = 32.0±0.26MSH/day. This implies that sunspots on the mean follow a parabolic decay law; the traditional linear decay law is excluded by the data. The validity of the Gnevyshev–Waldmeier rela...

Laser-Doppler velocity measurements in water are reported for the flow in the plane of symmetry of a turbulent spot. The unsteady mean flow, defined as an ensemble average, is fitted to a conical growth law by using data at three streamwise stations to determine the virtual origin in x and t. The two-dimensional unsteady stream function is expressed as 1fr = U~ tg(£, r/) in conical similarity c...