Analysis of two-dimensional incompressible flow past airfoils using unsteady Navier-Stokes equations

The conservative form of the unsteady Navier-Stokes equations in terms of vorticity and stream function in generalized curvilinear coordinates are used to analyze the flow structure of steady separation and unsteady flow with massive separation. The numerical method solves the discretized equations using an ADI-BGE method. The method is applied to a symmetric 12 percent thick Joukowski airfoil. A conformal clustered grid is generated; several 1-D stretching transformations are used to obtain a grid that attempts to resolve many of the multiple scales of the unsteady flow with massive separation, while maintaining the transformation metrics to be smooth and continuous in the entire flow field. Detailed numerical results are obtained for three flow configurations (1) Re = 1000, alpha = 5 deg., (2) Re =1000, alpha = 15 deg., (3) Re = 10,000, alpha = 5 deg. No artificial dissipation was added; however, lack of a fine grid in the normal direction has presently led to results which are considered qualitative, especially for case (3)

Simulation of self-induced unsteady motion in the near wake of a Joukowski airfoil

The unsteady Navier-Stokes analysis is shown to be capable of analyzing the massively separated, persistently unsteady flow in the post-stall regime of a Joukowski airfoil for an angle of attack as high as 53 degrees. The analysis has provided the detailed flow structure, showing the complex vortex interaction for this configuration. The aerodynamic coefficients for lift, drag, and moment were calculated. So far only the spatial structure of the vortex interaction was computed. It is now important to potentially use the large-scale vortex interactions, an additional energy source, to improve the aerodynamic performance

Characterization of dynamic stall phenomenon using two-dimensional unsteady Navier-Stokes equations

Among the new significant aspects of the present work are: (1) the treatment of the far-field boundary; (2) the use of C-grid topology, with the branch-cut singularity treated analytically; (3) evaluation of the effect of the envelope of prevailing initial states, and finally; (4) the ability to employ streakline/pathline 'visualization' to probe the unsteady features prevailing in vortex-dominated flows. The far-field boundary is placed at infinity, using appropriate grid stretching. This contributes to the accuracy of the solutions, but raised a number of important issues which needed to be resolved; this includes determining the equivalent time-dependent circulation for the pitching airfoil. A secondary counter-clockwise vortex erupts from within the boundary layer and immediately pinches off the energetic leading-edge shear layer which then, through hydrodynamic instability, rolls up into the dynamic stall vortex. The streakline/pathline visualization serves to provide information for insight into the physics of the unsteady separated flow

Strong and auxiliary forms of the semi-Lagrangian method for incompressible flows

We present a review of the semi-Lagrangian method for advection-diusion and incompressible Navier-Stokes equations discretized with high-order methods. In particular, we compare the strong form where the departure points are computed directly via backwards integration with the auxiliary form where an auxiliary advection equation is solved instead; the latter is also referred to as Operator Integration Factor Splitting (OIFS) scheme. For intermediate size of time steps the auxiliary form is preferrable but for large time steps only the strong form is stable

Geometric Mixing, Peristalsis, and the Geometric Phase of the Stomach

Mixing fluid in a container at low Reynolds number - in an inertialess environment - is not a trivial task. Reciprocating motions merely lead to cycles of mixing and unmixing, so continuous rotation, as used in many technological applications, would appear to be necessary. However, there is another solution: movement of the walls in a cyclical fashion to introduce a geometric phase. We show using journal-bearing flow as a model that such geometric mixing is a general tool for using deformable boundaries that return to the same position to mix fluid at low Reynolds number. We then simulate a biological example: we show that mixing in the stomach functions because of the "belly phase": peristaltic movement of the walls in a cyclical fashion introduces a geometric phase that avoids unmixing.Comment: Revised, published versio

EHA evaluation of the ESMO-Magnitude of Clinical Benefit Scale version 1.1 (ESMO-MCBS v1.1) for haematological malignancies

Objective Value frameworks in oncology have not been validated for the assessment of treatments in haematological malignancies, but to avoid overlaps and duplications it appears reasonable to build up experience on existing value frameworks, such as the European Society for Medical Oncology-Magnitude of Clinical Benefit Scale (ESMO-MCBS). Methods Here we present the results of the first feasibility testing of the ESMO-MCBS v1.1 for haematological malignancies based on the grading of 80 contemporary studies for acute leukaemia, chronic leukaemia, lymphoma, myeloma and myelodysplastic syndromes. The aims were (1) to evaluate the scorability of data, (2) to evaluate the reasonableness of the generated grades for clinical benefit using the current version and (3) to identify shortcomings in the ESMO-MCBS v1.1 that require amendments to improve the efficacy and validity of the scale in grading new treatments in the management of haematological malignancies. Results In general, the ESMO-MCBS v1.1 was found to be widely applicable to studies in haematological malignancies, generating scores that were judged as reasonable by European Hematology Association (EHA) experts. A small number of studies could either not be graded or were not appropriately graded. The reasons, related to the differences between haematological and solid tumour malignancies, are identified and described. Conclusions Based on the findings of this study, ESMO and EHA are committed to develop a version of the ESMO-MCBS that is validated for haematological malignancies. This development process will incorporate all of the usual stringencies for accountability of reasonableness that have characterised the development of the ESMO-MCBS including field testing, statistical modelling, evaluation for reasonableness and openness to appeal and revision. Applying such a scale will support future public policy decision-making regarding the value of new treatments for haematological malignancies and will provide insights that could be helpful in the design of future clinical trials

EHA evaluation of the ESMO—Magnitude of Clinical Benefit Scale version 1.1 (ESMO-MCBS v1.1) for haematological malignancies

Objective: Value frameworks in oncology have not been validated for the assessment of treatments in haematological malignancies, but to avoid overlaps and duplications it appears reasonable to build up experience on existing value frameworks, such as the European Society for Medical Oncology—Magnitude of Clinical Benefit Scale (ESMO-MCBS). Methods: Here we present the results of the first feasibility testing of the ESMO-MCBS v1.1 for haematological malignancies based on the grading of 80 contemporary studies for acute leukaemia, chronic leukaemia, lymphoma, myeloma and myelodysplastic syndromes. The aims were (1) to evaluate the scorability of data, (2) to evaluate the reasonableness of the generated grades for clinical benefit using the current version and (3) to identify shortcomings in the ESMO-MCBS v1.1 that require amendments to improve the efficacy and validity of the scale in grading new treatments in the management of haematological malignancies. Results: In general, the ESMO-MCBS v1.1 was found to be widely applicable to studies in haematological malignancies, generating scores that were judged as reasonable by European Hematology Association (EHA) experts. A small number of studies could either not be graded or were not appropriately graded. The reasons, related to the differences between haematological and solid tumour malignancies, are identified and described. Conclusions: Based on the findings of this study, ESMO and EHA are committed to develop a version of the ESMO-MCBS that is validated for haematological malignancies. This development process will incorporate all of the usual stringencies for accountability of reasonableness that have characterised the development of the ESMO-MCBS including field testing, statistical modelling, evaluation for reasonableness and openness to appeal and revision. Applying such a scale will support future public policy decision-making regarding the value of new treatments for haematological malignancies and will provide insights that could be helpful in the design of future clinical trials

Radio emission of highly inclined cosmic ray air showers measured with LOPES

LOPES-10 (the first phase of LOPES, consisting of 10 antennas) detected a significant number of cosmic ray air showers with a zenith angle larger than 50$^{\circ}$, and many of these have very high radio field strengths. The most inclined event that has been detected with LOPES-10 has a zenith angle of almost 80$^{\circ}$. This is proof that the new technique is also applicable for cosmic ray air showers with high inclinations, which in the case that they are initiated close to the ground, can be a signature of neutrino events.Our results indicate that arrays of simple radio antennas can be used for the detection of highly inclined air showers, which might be triggered by neutrinos. In addition, we found that the radio pulse height (normalized with the muon number) for highly inclined events increases with the geomagnetic angle, which confirms the geomagnetic origin of radio emission in cosmic ray air showers.Comment: A&A accepte