Lift and drag evaluation in translating and rotating non-inertial systems

In this paper relationships have been derived for lift and drag coefficients for cylindrical bodies for two cases. The relative motion between the body and the fluid is assumed to be two-dimensional and to take place in a plane perpendicular to the axis of the body. Three-dimensional effects are ignored, thus limiting the validity of the formulae to low Reynolds number flows. The fluid is assumed to be an incompressible constant- property Newtonian fluid. In the first case, an inertial system is fixed to a stationary cylindrical body. The motion of the fluid in which the body is placed is an arbitrary function of time not identically zero, e.g. the fluid can have linear and angular acceleration, such as translation, oscillation or rotation. The velocity of the fluid at a single instant is either uniform in space or, in the case of rotation, a linear function of distance from the origin of the system. In the second case, a noninertial system is fixed to an accelerating cylindrical body. The relative flow between fluid and body is kinematically the same as in the first case, but the forces acting upon the bodies differ in the two systems. This is due to the inertial forces that occur in a noninertial system. General formulae are derived for a cylindrical body of arbitrary cross-section and give the relationships between the two systems for each set of coefficients, i.e. the relationship between the lift coefficients for each case, and the same for the drag coefficient. As an example, the relationships are applied to two common cases, a circular and a rectangular cross-section cylinder

Numerical study of surface tension driven convection in thermal magnetic fluids

Microgravity conditions pose unique challenges for fluid handling and heat transfer applications. By controlling (curtailing or augmenting) the buoyant and thermocapillary convection, the latter being the dominant convective flow in a microgravity environment, significant advantages can be achieved in space based processing. The control of this surface tension gradient driven flow is sought using a magnetic field, and the effects of these are studied computationally. A two-fluid layer system, with the lower fluid being a non-conducting ferrofluid, is considered under the influence of a horizontal temperature gradient. To capture the deformable interface, a numerical method to solve the Navier???Stokes equations, heat equations, and Maxwell???s equations was developed using a hybrid level set/ volume-of-fluid technique. The convective velocities and heat fluxes were studied under various regimes of the thermal Marangoni number Ma, the external field represented by the magnetic Bond number Bom, and various gravity levels, Fr. Regimes where the convection were either curtailed or augmented were identified. It was found that the surface force due to the step change in the magnetic permeability at the interface could be suitably utilized to control the instability at the interface.published or submitted for publicationis peer reviewe

Aeronautical Engineering: A special bibliography with indexes, supplement 67, February 1976

This bibliography lists 341 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1976

Wind tunnel wall interference (January 1980 - May 1988): A selected, annotated bibliography

This selected bibliography lists 423 entries on the subject of wall interference during testing in wind tunnels. It is the third in a series of bibliographies on the subject. The first, NASA TM-87639, August 1986, is concerned with the reduction of wall interference by the use of adaptive walls. The second, NASA TP-89066, December 1986, is on wall interference in V/STOL and high lift testing. This, the third in the series, covers the wall interference literature published during the period January 1980 through May 1988, generally excluding those topics covered in the first two parts

A moving control volume approach to computing hydrodynamic forces and torques on immersed bodies

We present a moving control volume (CV) approach to computing hydrodynamic forces and torques on complex geometries. The method requires surface and volumetric integrals over a simple and regular Cartesian box that moves with an arbitrary velocity to enclose the body at all times. The moving box is aligned with Cartesian grid faces, which makes the integral evaluation straightforward in an immersed boundary (IB) framework. Discontinuous and noisy derivatives of velocity and pressure at the fluid-structure interface are avoided and far-field (smooth) velocity and pressure information is used. We re-visit the approach to compute hydrodynamic forces and torques through force/torque balance equation in a Lagrangian frame that some of us took in a prior work (Bhalla et al., J Comp Phys, 2013). We prove the equivalence of the two approaches for IB methods, thanks to the use of Peskin's delta functions. Both approaches are able to suppress spurious force oscillations and are in excellent agreement, as expected theoretically. Test cases ranging from Stokes to high Reynolds number regimes are considered. We discuss regridding issues for the moving CV method in an adaptive mesh refinement (AMR) context. The proposed moving CV method is not limited to a specific IB method and can also be used, for example, with embedded boundary methods

Aeronautical engineering: A continuing bibliography, supplement 122

This bibliography lists 303 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1980

Mono-Dispersed Droplet Delivery in a Refrigerated Wind Tunnel

An aircraft may experience inlight ice accretion and corresponding reductions in performance and control when the vehicle encounters clouds of super-cooled water droplets. In order to study anti-icing coatings, the EADS-IW Surface Engineering Group is building a refrigerated wind tunnel. Several variations of droplet delivery systems were explored to determine the most effective way to introduce mono-dispersed droplets into the wind tunnel. To investigate this flow, timeurate, unsteady viscous flow simulations were performed using the Loci/CHEM flow solver with a multi-scale hybrid RANS/LES turbulence model. A Lagrangian droplet model was employed to simulate the movement of water droplets in the wind tunnel. It was determined that the droplet delivery system required pressure relief to properly orient the flow inside the droplet delivery tube. Additionally, a streamlined drop tube cross-section was demonstrated to reduce turbulence in the wake and decrease the variability in droplet trajectories in the test section

Numerical and experimental analysis of a thin liquid film on a rotating disk related to development of a spacecraft absorption cooling system

The numerical and experimental analysis of a thin liquid film on a rotating and a stationary disk related to the development of an absorber unit for a high capacity spacecraft absorption cooling system, is described. The creation of artificial gravity by the use of a centrifugal field was focused upon in this report. Areas covered include: (1) One-dimensional computation of thin liquid film flows; (2) Experimental measurement of film height and visualization of flow; (3) Two-dimensional computation of the free surface flow of a thin liquid film using a pressure optimization method; (4) Computation of heat transfer in two-dimensional thin film flow; (5) Development of a new computational methodology for the free surface flows using a permeable wall; (6) Analysis of fluid flow and heat transfer in a thin film in the presence and absence of gravity; and (7) Comparison of theoretical prediction and experimental data. The basic phenomena related to fluid flow and heat transfer on rotating systems reported here can also be applied to other areas of space systems

A survey of computational aerodynamics in the United States

Programs in theoretical and computational aerodynamics in the United States are described. Those aspects of programs that relate to aeronautics are detailed. The role of analysis at various levels of sophistication is discussed as well as the inverse solution techniques that are of primary importance in design methodology. The research is divided into the broad categories of application for boundary layer flow, Navier-Stokes turbulence modeling, internal flows, two-dimensional configurations, subsonic and supersonic aircraft, transonic aircraft, and the space shuttle. A survey of representative work in each area is presented