Research areas

The Institute SLA is structured into four research areas/groups: Dynamics of drops and sprays, modelling and simulation of turbulent flows, dynamics of particle-laden flows, and flow control and unsteady aerodynamics.

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Dynamics of drops and sprays

Flows in drops and sprays are governed by inertial effects, viscosity, surface tension and wettability. We study the phenomena experimentally, theoretically and with the help of CFD codes.

Head of research group

  Name Contact
Apl. Prof. Dr. Ilia Roisman
+49 6151 16-22173
L2|06 312

The research activities of the group include experimental investigation, theoretical analysis and CFD computations of the flows in drops and sprays, governed by inertial effects, viscosity, surface tension and wettability. Among the main studied phenomena are:

Breakup, splash and atomization of liquid drops

  • Fuel injection
  • Splash of an impacting drop
  • Secondary atomization
  • Stability analysis

Collision phenomena

  • Drop impact onto a dry or wetted wall
  • Binary drop collisions
  • Phenomena in drops, films and rivulets driven by aerodynamic forces

Heat transfer and phase change phenomena

  • Spray cooling
  • Physics of icing

Wetting and dewetting phenomena

  • Motion of a wall bound liquid drop, film and rim
  • Propagation of rivulets in a corner
  • Liquid imbibition in porous media

Publications

Web of Science ResearcherID E-9917-2015

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Modelling and simulation of turbulent flows

The group has extensive experience in the field of numerical simulation of complex flow configurations, which is illustrated in numerous scientific and industry-relevant projects.

Head of research group

  Name Contact
Apl. Prof. Dr.-Ing. habil. Suad Jakirlic
+49 6151 16-22171
L2|06 413

The research activities of the group concentrate on both simulation methodology (novel turbulence models including own developments) as well as on the flow structure to be captured. Relevant cases exhibit large complexity of the structural flow properties with respect to differently varying straining.

Simulation methodology

Novel turbulence models of various types:

  • conventional RANS (Reynolds-Averaged Navier-Stokes) concept: the main focus is on the dynamics of the entire Reynolds stress tensor
  • eddy-resolving, hybrid RANS/LES (Large-Eddy Simulation) modeling strategy: zonal (RANS-based, wall-modeled LES) and seamless formulations
  • numerous own developments

Examples of treated flow configurations

  • transitional and fully-turbulent flows
  • flows subjected to different pressure gradients (deceleration → approaching separation and acceleration → approaching laminarization), separating and reattaching flows
  • flows subjected to varying temperature gradients; mixing under conditions of variable fluid properties
  • two-phase flows: gaseous/solid (particle transport, particle erosion) and gaseous/liquid (evaporation, bubbly flows)
  • swirling and tumbling flows, mean compression
  • flows over rough and porous walls
  • airplane (subsonic and transonic configurations) and car aerodynamics
  • active flow separation control by boundary layer forcing, plasma-actuated flow control
  • physiologically pulsating flow in blood vessels

Flow configurations computed by VLES (Very LES) and PANS (Partially-Averaged Navier- Stokes): natural decay of homogeneous isotropic turbulence (a, VLES and PANS), flow in a channel with rough walls (b, VLES), flow in a vortex pipe representing a cooling hole of a turbine blade (c, VLES and PANS), flow impingement onto a heated wall (d, VLES), flow in an IC-engine (e, VLES and PANS), flow past a rotating cylinder (f, VLES and PANS), thermal mixing in a T-junction (g, VLES), single car aerodynamics (h, VLES and PANS), overtaking manoeuver (i, PANS)

Flow configurations computed by the eddy-resolving URANS RSM (Reynolds-stress model): a) physiological flow in an aortic aneurysm model, b) flow past a tandem cylinder, c) separating flow in a channel with periodic axisymmetric constrictions, d) flow past a plunging aerofoil (also with plasmaactuated leading-edge-vortex manipulation), e) flow in a 3D diffuser, f) plasma-actuated (with 100% duty cycle) restructuring of the secondary motion in the inflow duct of the 3D diffuser (only one half of the duct is shown), g) far-field noise illustrated by the PSD of acoustic pressure in the tandem cylinder flow configuration and f) flow in a square cross-sectioned bubble column

Literature

An illustration of our modeling activities based on the calculations of different flow configurations can be found in the following manuscript:

Jakirlić, S., Bopp, M., Chang, C.-Y., Köhler, F., Krumbein, B., Kutej, L., Kütemeier, D., Maden, I., Maduta, R., Ullrich, M., Wegt, S. and Tropea, C. (December 2019):
RANS-based Sub-scale Modelling in Eddy-resolving Simulation Methods. (opens in new tab) ERCOFTAC Bulletin, Vol. 121, pp. 5-18

Further relevant publications can be found under:

https://scholar.google.de/citations?user=SLRGW_IAAAAJ&hl=de

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Dynamics of particle-laden flows

The research group focuses on laser-optical and imaging techniques for the measurement of flows.

Head of research group

  Name Working area(s) Contact
Prof. Dr.-Ing. Jeanette Hussong
Head of Institute
Dynamics of particle-laden flows, flow measurement techniques
+49 6151 16-22174
L2|06 417

Research activities of the group include the application, combination of laser-based imaging techniques to access the interaction between particles and flow with high spatial and temporal resolution. The research activities concentrate on:

  • Migration and segregation dynamics of microparticles in shear flows
  • Multidimensional fractionation of microparticles
  • Dissolution behavior of metallic particles in swirling flows
  • Forced wetting and dewetting of complex fluids
  • Mixing, transport and deposition in thin films
  • Wall interaction of particle laden, turbulent flows
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Flow control and unsteady aerodynamics

We investigate methods to optimize flow using generic configurations. Our results help to reduce aerodynamic fatigue loading on wind turbines, for example.

Head of research group

  Name Working area(s) Contact
Prof. Dr.-Ing. Jeanette Hussong
Head of Institute
Dynamics of particle-laden flows, flow measurement techniques
+49 6151 16-22174
L2|06 417
Smoke visualization of the leading edge vortex growing on a pitching and plunging NACA airfloil
Smoke visualization of the leading edge vortex growing on a pitching and plunging NACA airfloil

Unsteady aerodynamics deal with aerodynamic forces on bodies when they experience transient inflow conditions. Fluctuations can arise from transient inflow conditions on a steady body or from a motion of the body in steady inflow and result in fluctuations of aerodynamic loads.

Gusty inflow conditions on wind turbine blades or atmospheric turbulence on aircraft wings represent examples in which transient inflow conditions lead to unsteady aerodynamic loads and resulting structural loads. In the context of biological flapping flight, idealized by a moving body in steady inflow, unsteady aerodynamic effects, and in particular the so-called leading edge vortex, enable unrivaled lift and manoeuvrability.

Flow field measurement (PIV) on a pitching and plunging NACA airfoil
Flow field measurement (PIV) on a pitching and plunging NACA airfoil

Current research efforts focus on a prediction of unsteady aerodynamic loads with the aid of analytical transfer functions as well as the investigation of the leading edge vortex.

Corresponding investigations make use of different experimental setups in combination with different wind tunnels. This allows highly dynamic motion kinematics of airfoils in wind tunnels and the generation of gusty inflow conditions. A broad range of measurement techniques such as time-resolved particle image velocimetry, laser Doppler anemometry, transient pressure measurement and hot-wire anemometry allows a measurements of transient phenomena.

Numerical flow simulations complement and extend the experimental research work.

Based on a deeper understanding of gust loads and the leading edge vortex, active and passive flow control approaches for both scenarios are considered.

This includes reaearch activities to mitigate unsteady aerodynamic gust loads on wind turbine blades by passive camber mechanisms of airfoils (Adaptive Camber Airfoil). Manipulation of the leading edge vortex with the aid of dielectric barrier discharge plasma actuators for lift enhancement in biological flapping flight is also subject to current research.

Numerical flow simulations are used intensively in the area of unsteady flow control, complementary to experimental investigations.

Research projects

Overview of the institute's research projects .