Over the past decade significant strides have been made in the development of pulse burst laser systems capable of producing high energy laser pulses at repetition rates in excess of 1 MHz. These unique laser systems are currently being used in experiments across a variety of fields ranging from traditional fluid dynamics to combustion to plasma physics. Described here is the use of one such sy...

The paper evaluates a new method to prescribe synthesized turbulent inlet boundary conditions. The method can also be used when prescribing turbulent fluctuations at an interface between (U)RANS and LES regions when the flow enters the LES region. When making LES, DES or hybrid LES-RANS a precursor channel DNS is often used. The disadvantage of this method is that it is difficult to re-scale th...

The origins of solar magnetism lie below the visible surface of the Sun, in the highly turbulent convection zone. Turbulent convection operates in conjunction with rotational shear, global circulations and intricate boundary layers to produce the rich diversity of magnetic activity we observe. Here, we review recent insights into the operation of the solar dynamo obtained from solar and stellar...

We present a reformulation of unsteady turbulent flow simulations. The initial condition is relaxed and information is allowed to propagate both forward and backward in time. Simulations of chaotic dynamical systems with this reformulation can be proven to be well-conditioned time domain boundary value problems. The reformulation can enable scalable parallel-in-time simulation of turbulent flows.

A laminar boundary layer separates in a region of adverse pressure gradient, undergoes transition, and finally the turbulent boundary layer reattaches, forming a laminar separation bubble (LSB). Laminar-turbulent transition within such a LSB is investigated by means of Laser-Doppler-Anemometry (LDA), Particle Image Velocimetry (mono PIV and stereoscopic PIV (SPIV)) and direct numerical simulati...

In this paper, we study the influence on the ring-like vortex structure in MVG controlled supersonic ramp flow by different inflow conditions. In front of the MVG, three turbulent inflow profiles with different boundary layer thickness are generated as the inflow. From the shape factors, we can see that these inflows in front of the MVG are fully developed turbulent. It is found that the inflow...

Today, whereas aeronautical CFD applications are mainly based on Reynolds Average Navier-Stokes modeling, Large Eddy Simulation (L.E.S.) is becoming more used for some of them. LES needs the instantaneous inlet velocity as turbulent inflow boundary conditions which motivates the implementation and validation of a synthetic turbulent inflow condition for LES. The so called "Synthetic Eddy Method...

In turbulent Taylor-Couette flow, the injection of bubbles reduces the overall drag. On the other hand, rough walls enhance the overall drag. In this work, we inject bubbles into turbulent Taylor-Couette flow with rough walls (with a Reynolds number up to 4 x 10(5), finding an enhancement of the dimensionless drag as compared to the case without bubbles. The dimensional drag is unchanged. As in...

Advances in the visualization and prediction of turbulence are shedding new light on mass transfer in the turbulent boundary layer. These discoveries have important implications for many topics in environmental science and engineering, from the transport of earth-warming CO2 across the sea-air interface, to nutrient processing and sediment erosion in rivers, lakes, and the ocean, to pollutant r...

A random flow generation (RFG) technique is presented, which can be used for initial/inlet boundary generation in LES (Large-Eddy-Simulations) or particle tracking in LES/RANS (Reynolds-Averaged Navier-Stokes) computations of turbulent flows. The technique is based on previous methods of synthesizing divergencefree vector fields from a sample of Fourier harmonics and allows to generate nonhomog...