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The flow over alternating roughness strips oriented normally to the mean stream is studied using wall-modeled large-eddy simulations (WMLES) and improved delayed detached-eddy simulations (IDDES) (a hybrid method solving the Reynolds-averaged Navier–Stokes (RANS) equations near the wall and switching to large-eddy simulations (LES) in the core of the flow). The calculations are performed in an open-channel configuration. Various approaches are used to account for roughness by either modifying the wall boundary condition for WMLES or the model itself for IDDES or by adding a drag forcing term to the momentum equations. By comparing the numerical results with the experimental data, both methods with both roughness modifications are shown to reproduce the non-equilibrium effects, but noticeable differences are observed. The WMLES, although affected by the underlying equilibrium assumption, predicts the return to equilibrium of the skin friction in good agreement with the experiments. The velocity predicted by the IDDES does not have memory of the upstream conditions and recovers to the equilibrium conditions faster. Memory of the upstream conditions appears to be a critical factor for the accurate computational modeling of this flow.

Computational fluid dynamics is employed to predict the aerodynamic properties of the prototypical trailing-edge control surfaces for a small, regional transport, commercial aircraft. The virtual experiments are performed at operational flight conditions, by resolving the mean turbulent flow field around a realistic model of the whole aircraft. The Reynolds-averaged Navier–Stokes approach is used, where the governing equations are solved with a finite volume-based numerical method. The effectiveness of the flight control system, during a hypothetical conceptual pre-design phase, is studied by conducting simulations at different angles of deflection, and examining the variation of the aerodynamic loading coefficients. The proposed computational modeling approach is verified to have good practical potential, also compared with reference industrial data provided by the Leonardo Aircraft Company.

This study focused on numerical simulations of flow over rough walls using wall models for Large-Eddy Simulation (LES). Wall-modeled simulations are necessary due to the high computational cost of resolving flows at high Reynolds numbers, particularly with roughness. While wall models have been effective in turbulent flow simulations, their true predictive capability must be assessed in scenarios with nonequilibrium effects. The aim here is to evaluate various wall models’ performance in LES for predicting flows influenced by changes in surface roughness or pressure gradients.Wall-modelled Large-Eddy Simulations (WMLESs) have been performed with the log-law based Equilibrium Wall Model (EQWM), and the Generalized Moody Diagram (GMD) model [Meneveau, J. Turbul. 21(11):650–673 , 2020]. Furthermore, Improved Delayed Detached-Eddy Simulation (IDDES) [Shur et al., Int. J. Heat Fluid Flow, Vol. 29, pp. 1638-1649, 2008] and Integral Wall-modelled Large-Eddy Simulations (iWMLESs) were conducted. The Drag Model (DM) of Varghese and Durbin [J. Fluid Mech., Vol. 897, pp. A10, 2020] is also used in conjunction with both the EQWM and IDDES. The Lagrangian Relaxation Towards Equilibrium (LaRTE) [Fowler et al., J. Fluid Mech. 934:A44, 2022] model, was considered as representative of iWMLES, which distinguishes between quasi-equilibrium wall stress evolution and non-equilibrium effects. A novel formulation of LaRTE for rough walls was introduced to facilitate a seamless transition between behaviors characteristic of smooth and rough flow conditions.Results showed the memory feature of the log-law based EQWM in its smooth adaptation to the new surface condition, while IDDES exhibited non-physical adjustments in the mean velocity profile after surface transitions. The newly extended LaRTE model for rough surfaces proved essential for capturing flow field discontinuities induced by surface heterogeneity, outperforming other conventional wall models. The performance of wall models appears to be quite satisfactory across a range of pressure gradient applications, covering scenarios from mild to strong pressure gradients, including transitions between favorable pressure gradient (FPG) to adverse pressure gradient (APG) and vice versa. However, challenges persist in accurately capturing the flow evolution in the APG region, and further study is needed to explore the applicability of smooth-walls flow assumptions for roughness modelling.

This study investigated the clinical relevance of acute pancreatitis in allogeneic hemopoietic stem cell (bone marrow or peripheral blood) transplants (BMT). We studied 26 patients undergoing BMT. The preparative regimen was busulfan and cyclophosphamide in 17 patients and total body irradiation and cyclophosphamide in 9 patients. Graft-versus-host disease (GVHD) prophylaxis consisted of cyclosporin A and short-term methotrexate in all 26 patients. The pancreas was studied using amylase and lipase serum levels, abdominal contrast-enhanced tomography, and/or ultrasound. Clinical and laboratory signs of acute pancreatitis were found in two patients with acute hepatointestinal GVHD, and in one patient with acute hepatic GVHD and cytomegalovirus infection. This patient died of multiorgan failure, with interstitial acute pancreatitis at autopsy; the other two patients recovered with general supportive care and GVHD therapy. We suggest that in the patients with complications after BMT, particularly acute hepatic/hepatointestinal GVHD, and cytomegalovirus infection, the possibility of acute pancreatitis should be considered.

We evaluated the alveolar-arterial oxygen difference (deltaA-a) and the ratio between PaO2 and the fractional concentration of inspired oxygen (P/F) in acute pancreatitis. Eleven patients had mild uncomplicated disease, six showed acute abdominal fluid collections, six had acute abdominal collections and asymptomatic x-ray lung involvement, three presented transient dyspneic episodes, and four had severe acute pancreatitis requiring prolonged oxygen therapy. In the uncomplicated disease, respiratory function was normal; in the six patients with abdominal collections only, deltaA-a increased by 50% and P/F decreased by 20-30%; in the six patients with abdominal collections and asymptomatic x-ray lung involvement, deltaA-a increased by 50-70% and P/F decreased by 40%; the three patients with dyspneic episodes showed a twofold increase in deltaA-a and a 40% decrease in P/F; the four patients with severe pancreatitis had a two- to threefold increase in deltaA-a and a 40-50% decrease in P/F. Hence respiratory function is normal only in uncomplicated pancreatitis; in the presence of complications, disturbance of gas exchange always occurs, requiring careful control and treatment.

BackgroundThe surgical resection of the splenic flexure carcinoma (SFC) is challenging and the optimal surgical procedure for SFCs remains a matter of debate. The present study aimed to compare in a multicenter European sample of patients the short- and long-term outcomes of extended right (ERC) vs. left (LC) vs. segmental left colectomy (SLC) for SFCs.MethodsThis retrospective multicenter study analyzed the surgical and oncological outcomes of SFC patients undergoing elective curative intent surgery between 2000 and 2018. Descriptive and exploratory analyses were first conducted on the whole sample. Outcomes of the different procedures (ERC vs. LC vs. SLC) were then compared using propensity score matching for multilevel treatment. Overall (OS) and disease-free survival (DFS) were evaluated by Kaplan–Meier method.ResultsFrom a total of 399 SFC patients, 143 (35.8%) underwent ERC, 131 (32.8%) underwent LC, and 125 (31.4%) underwent SLC. Overall, 297 (74.4%) were laparoscopic procedures. An increase in operative time, time to flatus, time to regular diet, and hospital stay was observed with the progressive extension of SFC resection. ERC was associated with significantly increased risk of postoperative ileus compared to both LC and SLC. A significantly greater number of lymph nodes were retrieved by ERC, but the objective of at least 12 retrieved lymph nodes was achieved in 85% of patients, without procedure-related differences. No differences were observed in OS or DFS between ERC, LC, and SLC.ConclusionThe present study supports the resection of SFCs by colon-sparing surgical techniques, such as SLC.

BackgroundSeveral reports demonstrated a strong association between the level of adherence to the protocol and improved clinical outcomes after surgery. However, it is difficult to obtain full adherence to the protocol into clinical practice and has still not been identified the threshold beyond which improved functional results can be reached.MethodsThe ERCOLE (ERas and COLorectal Endoscopic surgery) study was as a cohort, prospective, multi-centre national study evaluating the association between adherence to ERAS items and clinical outcomes after minimally invasive colorectal surgery. The primary endpoint was to associate the percentage of ERAS adherence to functional recovery after minimally invasive colorectal cancer surgery. The secondary endpoints of the study was to validate safety of the ERAS programme evaluating complications’ occurrence according to Clavien-Dindo classification and to evaluate the compliance of the Italian surgeons to each ERAS item.Results1138 patients were included. Adherence to the ERAS protocol was full only in 101 patients (8.9%), > 75% of the ERAS items in 736 (64.7%) and > 50% in 1127 (99%). Adherence to > 75% was associated with a better functional recovery with 90.2 ± 98.8 vs 95.9 ± 33.4 h (p = 0.003). At difference, full adherence to the ERAS components 91.7 ± 22.1 vs 92.2 ± 31.6 h (p = 0.8) was not associated with better recovery.ConclusionsOur results were encouraging to affirm that adherence to the ERAS program up to 75% could be considered satisfactory to get the goal. Our study could be considered a call to simplify the ERAS protocol facilitating its penetrance into clinical practice.

Background Despite advances and improvements in the management of surgical patients, emergency and trauma surgery is associated with high morbidity and mortality. This may be due in part to delays in definitive surgical management in the operating room (OR). There is a lack of studies focused on OR prioritization and resource allocation in emergency surgery. The Operating Room management for emergency Surgical Activity (ORSA) study was conceived to assess the management of operating theatres and resources from a global perspective among expert international acute care surgeons. Method The ORSA study was conceived as an international web survey. The questionnaire was composed of 23 multiple-choice and open questions. Data were collected over 3 months. Participation in the survey was voluntary and anonymous. Results One hundred forty-seven emergency and acute care surgeons answered the questionnaire; the response rate was 58.8%. The majority of the participants come from Europe. One hundred nineteen surgeons (81%; 119/147) declared to have at least one emergency OR in their hospital; for the other 20/147 surgeons (13.6%), there is not a dedicated emergency operating room. Forty-six (68/147)% of the surgeons use the elective OR to perform emergency procedures during the day. The planning of an emergency surgical procedure is done by phone by 70% (104/147) of the surgeons. Conclusions There is no dedicated emergency OR in the majority of hospitals internationally. Elective surgical procedures are usually postponed or even cancelled to perform emergency surgery. It is a priority to validate an effective universal triaging and scheduling system to allocate emergency surgical procedures. The new Timing in Acute Care Surgery (TACS) was recently proposed and validated by a Delphi consensus as a clear and reproducible triage tool to timely perform an emergency surgical procedure according to the clinical severity of the surgical disease. The new TACS needs to be prospectively validated in clinical practice. Logistics have to be assessed using a multi-disciplinary approach to improve patients' safety, optimise the use of resources, and decrease costs.