Drag Assessment for Boundary Layer Control Schemes with Mass Injection

The present study considers uniform blowing in turbulent boundary layers as active flow control scheme for drag reduction on airfoils. The focus lies on the important question of how to quantify the drag reduction potential of this control scheme correctly. It is demonstrated that mass injection causes the body drag (the drag resulting from the stresses on the body) to differ from the wake survey drag (the momentum deficit in the wake of an airfoil), which is classically used in experiments as a surrogate for the former. This difference is related to the boundary layer control (BLC) penalty, an unavoidable drag portion which reflects the effort of a mass-injecting boundary layer control scheme. This is independent of how the control is implemented. With an integral momentum budget, we show that for the present control scheme, the wake survey drag contains the BLC penalty and is thus a measure for the inclusive drag of the airfoil, i.e. the one required to determine net drag reduction. The concept of the inclusive drag is extended also to boundary layers using the von Kàrmàn equation. This means that with mass injection the friction drag only is not sufficient to assess drag reduction also in canonical flows. Large Eddy Simulations and Reynolds-averaged Navier–Stokes simulations of the flow around airfoils are utilized to demonstrate the significance of this distinction for the scheme of uniform blowing. When the inclusive drag is properly accounted for, control scenarios previously considered to yield drag reduction actually show drag increase

3D-визуализация в ультразвуковой дефектоскопии

На сегодняшний день существует множество средств визуализации ультразвуковых данных, но все они, как правило, интегрированы в дефектоскопы. Когда у нас возникает потребность извлечь данные сканирования, произвести собственную обработку, и представить в трехмерном изображении, то мы оказываемся лишенными возможности визуализации. Предложенное программное обеспечение на основе алгоритма SAFT позволяет произвести постобработку данных сканирования (А-сканов) и двумерную и трехмерную визуализацию

Intestinal helminth infection drives carcinogenesis in colitis-associated colon cancer

Inflammatory bowel diseases (IBD) are chronic inflammatory disorders of the gastrointestinal tract, strongly associated with an increased risk of colorectal cancer development. Parasitic infections caused by helminths have been shown to modulate the host’s immune response by releasing immunomodulatory molecules and inducing regulatory T cells (Tregs). This immunosuppressive state provoked in the host has been considered as a novel and promising approach to treat IBD patients and alleviate acute intestinal inflammation. On the contrary, specific parasite infections are well known to be directly linked to carcinogenesis. Whether a helminth infection interferes with the development of colitis-associated colon cancer (CAC) is not yet known. In the present study, we demonstrate that the treatment of mice with the intestinal helminth Heligmosomoides polygyrus at the onset of tumor progression in a mouse model of CAC does not alter tumor growth and distribution. In contrast, H. polygyrus infection in the early inflammatory phase of CAC strengthens the inflammatory response and significantly boosts tumor development. Here, H. polygyrus infection was accompanied by long- lasting alterations in the colonic immune cell compartment, with reduced frequencies of colonic CD8+ effector T cells. Moreover, H. polygyrus infection in the course of dextran sulfate sodium (DSS) mediated colitis significantly exacerbates intestinal inflammation by amplifying the release of colonic IL-6 and CXCL1. Thus, our findings indicate that the therapeutic application of helminths during CAC might have tumor-promoting effects and therefore should be well-considered

Loading on rounded square foundation elements of offshore structures with marine growth at incidence

A systematic wind tunnel study is performed to identify the mean and fluctuating loads experienced by a 2D square prism with non-dimensional rounded edges of r=D = 0:16 and covered with hard marine fouling for Reynolds numbers between 70,000 and 8 million. The incidence angle is varied from a=-45 to 3.25 deg. with increments of 3.25 and 6.5 deg. . The critical angle of incidence, at which a reattachment of the free shear layer takes place on the lateral windward directed side surface, is found at acr =-6.5 deg. . For a acr. For the latter angles of incidence, a decrease towards -45 deg. induces higher values of CD and the r.m.s. of the lift fluctuations, as well as lower Strouhal numbers and mean lift forces

Bayesian Optimisation of blowing and suction for drag reduction on a transonic airfoil

Wall-normal blowing and suction has shown to be a promising active control method for friction drag reduction. In this work, we exploit a Bayesian optimization framework based on Gaussian process regression to find a configuration of non-homogeneous wall-normal blowing and suction capable of improving the aerodynamic efficiency of an RAE2822 airfoil in transonic conditions. The RANS simulations are carried out with the open-source solver SU2. During the optimization process, three different scenarios are considered: only the drag is minimized, the drag and the power needed to drive the control system are included, and the actuation power with a specified compressor efficiency are used for the calculation of the efficiency increase. Even in the most realistic case considering the actuation power and efficiencies an increase in the overall efficiency of 1.15% is reached.QC 20240122</p

Perfluorooctanesulfonic acid modulates barrier function and systemic T cell homeostasis during intestinal inflammation.

The intestinal epithelium is continuously exposed to deleterious environmental factors which might cause aberrant immune responses leading to inflammatory disorders. However, what environmental factors might contribute to disease are yet poorly understood. Here, to overcome the lack of in vivo models suitable for screening of environmental factors we used zebrafish reporters of intestinal inflammation. Using zebrafish, we interrogated the immunomodulatory effects of polyfluoroalkyl substances (PFAS), which have been positively associated with ulcerative colitis incidence. Exposure with perfluorooctanesulfonic acid (PFOS) during TNBS-induced inflammation enhances the expression of proinflammatory cytokines as well as neutrophil recruitment to the intestine of zebrafish larvae, which was validated in TNBS-induced colitis mice models. Moreover, PFOS exposure in mice undergoing colitis resulted in neutrophil-dependent increased intestinal permeability and enhanced PFOS translocation into circulation. Finally, this was associated with a neutrophil dependent expansion of systemic CD4+ T cells. Thus, our results indicate that PFOS worsens inflammation-induced intestinal damage with disruption of T cell homeostasis beyond the gut and provides a novel in vivo toolbox to screen for pollutants affecting intestinal homeostasis