Sponge Layer Research Articles

GENERATION OF LINEAR WAVES WITH BOTTOM WAVE MAKERS IN A FLUME: AN EFFICIENT WAY TO ABSORB REFLECTED WAVES

When waves are generated in a flume by the conventional piston or flap wave maker, waves reflected from structures will arrive at the wave maker and experience re-reflection. These re-reflected waves will propagate to the structures so that the target wave energy cannot be accurately obtained. Since 1980s, methods of internally generating waves inside a computational domain and putting sponge layers at the domain end have been developed in numerical modelling. Internally generated waves will propagate both directions from the wave generation zone and waves reflected from the structures will pass through the wave generation zone without any reflection by the wave maker and be absorbed in the sponge layers. Using the idea of internal generation of waves, Jung et al. (2018) developed bottom wave makers in a flume which have paddles moving up and down from the bottom (see also Lu et al. (2017)). In this study, following Jung et al.’s (2018) techniques, we numerically develop both rectangular and triangular bottom wave makers in a flume using the analytical method and the extended mild-slope equations.

Numerical study of wave-ice floe interactions and overwash by a meshfree particle method

The interaction between regular waves and ice floes under certain wave conditions involves overwash which is characterized by waves running up over the surface of an ice floe with large deformed free surfaces. An in-house moving particle semi-implicit (IMPS) method is employed to simulate the wave-ice floe interaction, especially for the specific behavior namely overwash due to a small freeboard of sea ice and a large body motion. In this work, a series of regular waves are generated using the Lagrangian particle method based on the Stokes wave theory. Models of the floating sea ice are simplified as circular disks without and with an edge barrier and a circular disk with a central hole, which can be used to study the influences of overwash. Hydrodynamic responses of the ice floe in regular wave conditions with different wave lengths and a constant wave height are analyzed. Compared with the mesh-based methods, the Lagrangian particle-based methods have advantages in treating highly deformed free surfaces during wave overwash processes. A piston-type wave maker and a sponge layer are applied for generating waves and avoiding the wave reflection from wall boundaries, respectively. Validations are presented including the circular ice floe with a diameter of 400 mm and a thickness of 15 mm interacting with regular waves with the wave length λ/D from 1.5 to 3.5. RAOs of the original circular disk are compared with those of the circular disks with an edge barrier and with a central hole. Overwash on the ice floe can be prevented by using an edge barrier. A new type of overwash which waves flow over the upper surface and then into the hole was proposed and simulated. The present results of numerical predictions are in good agreement with the experimental data and the published numerical results using the CFD code Flow-3D.

A general strategy to prepare transition metal sulfide functionalized hierarchically porous carbons with multiple enzyme-like activities for simultaneous electrochemical sensing of ATP metabolites

A general strategy for the in-situ hydrothermal synthesis of transition metal sulfides functionalized hierarchically porous carbons (FeS2-HPC, Co9S8-HPC, Ni3S2-HPC, Cu2S-HPC, and ZnS-HPC) is proposed using different transition metal chlorides as metal sources and activators, sustainable agroforestry waste biomass (Citrus sinensis peel sponge layer) as a carbon source, sulfuric acid as a sulfur source, and silica colloid as a hard template. The introduction of both transition metal salts and silica colloids facilitate the adjustment of the pore structure. The added sulfuric acid promotes the degradation of the agroforestry waste biomass, which are conducive to the formation of porous carbons. The in-situ synthesis of transition metal sulfide particles and the sulfur doping improve the conductivity, electrocatalytic and enzyme-like activities of obtained composite materials. The FeS2-HPC with multiple enzyme-like activities and the best electrocatalytic activity is applied as a nanozyme electrochemical sensing platform for the simultaneous detection of three ATP metabolites with a limit of detection (LOD) of 0.069 μM for uric acid in a linear range of 0.3–200 μM, a LOD of 0.047 μM for xanthine in 0.3–100 μM, and a LOD of 0.21 μM for hypoxanthine in 0.7–300 μM. This work provides a new idea for the development of transition metal sulfides functionalized porous carbons from agroforestry waste biomass, and a theoretical basis for the fabrication of nanozyme electrochemical sensing platform for health assessment and disease prevention.

Utilization the Aquatic Plants as a Filtration Media in A Closed Bio-Aquatic System to Improve Water Quality and Common carp Growth Performance

The experiment was conducted in the animal production field, College of Agriculture, Tikrit University, for the period from 14/6/2022 to 14/8/2022 inside a semi-exposed building with three treatments. Each treatment included three replicates, and each replicate included (6) fish in a closed bio-aquatic system, by weight 13.75±1.09, a filtration tank representing the mechanical and biological filter in an intensive aquatic system with a capacity of 100 liters each, two aquatic plants were grown Water thyme (Hydrilla Verticillata), Torpedo grass (Panicum Repens), except for the control treatment, which was similar to all treatments except for the presence of aquatic plants. The water was treated in a mechanical filter unit through sponge layer, then directing the water to the biological treatment by means of crushed gravel, in addition to the aquatic plants to filter the dissolved organic pollutants. The results showed a significant effect of aquatic plants at (p ≤0.05) on pH, Cloredait (Cl) nitrate (NO3,) nitrite (NO2), and ammonia. Water properties reflect to the biological system of organisms. There was a significant improvement in gain weight (G.W), specific growth rate (SGR), and feed conversion efficiency (FCR) for treatments T2 and T3 compared with control treatment. While, the result of the correlation or interactions between water characteristics with growth parameters for Common carp fish showed significant effects at (P ≤0.05) and (P ≤0.01) level.

Multifunctional chitosan/carbon dots/sodium alginate/zinc oxide double-layer sponge hydrogel with high antibacterial, mechanical and hemostatic properties

Due to the fact that bacterial contamination of wounds is the cause of increased morbidity and mortality today, various antimicrobial wound dressings are developing to prevent wound contamination. In addition, an ideal wound dressing should have proper mechanical and hemostatic properties to maintain wound healing conditions. Here, a double-layer sponge hydrogel nanocomposite wound dressing was designed and manufactured by combining zinc oxide nanoparticles (ZnONPs) with different concentrations in the hydrogel layer and green carbon dots in the sponge layer. The surface morphology of two layers was investigated using a scanning electron microscope. X-ray diffraction proved the presence of ZnONPs. Physical tests showed a decrease in water absorption and water vapor transmission rate and an increase in blood absorption in the presence of ZnO. The sponge layer showed suitable absorption support in the presence of carbon dots. By combining nanoparticles in both layers, the mechanical properties were greatly enhanced. The sponge hydrogel with the highest concentration of ZnO showed excellent inhibition of 41 mm against Pseudomonas aeruginosa bacteria and 25 mm of inhibition against Staphylococcus aureus. Finally, in vitro blood clotting and animal tests confirmed the increase in the hemostatic power of the sponge hydrogel with the maximum concentration of ZnO.

Gelatin and catechol-modified quaternary chitosan cotton dressings with rapid hemostasis and high-efficiency antimicrobial capacity to manage severe bleeding wounds

The development of functional wound dressings capable of both rapid hemostasis and high-efficiency antimicrobial is essential for the management of severe bleeding wounds. Cotton dressings are widely used in clinical practice; however, few dressings can simultaneously achieve rapid hemostasis and high-efficacy antimicrobial. Herein, a versatile cotton dressing (GCQCNF-5) was masterly developed by sequentially deposition catechol modified quaternary chitosan (CQCS) and gelatin onto a cotton nonwoven fabric (NF) surface. Because of the presence of a gelatin sponge layer with suitable thickness and porosity on its surface, GCQCNF-5 exhibits a notably enhanced hemostatic effect compared to NF both in vitro and in vivo, which is even slightly superior to that of MHS (a commercial gelatin hemostatic sponge). Moreover, after exerting a rapid hemostasis effect, GCQCNF-5 can further exploit CQCS to exert excellent immediate antimicrobial and long-lasting bacteriostatic effects. In vivo wound healing experiments further indicated that GCQCNF-5 could significantly promote rapid healing of infected wounds by effectively sterilizing, absorbing exudates, and providing moist healing environments. This study clearly demonstrated that GCQCNF-5 is a versatile wound dressing that can achieve simultaneously rapid hemostasis, high-efficiency antimicrobial, and promote rapid healing of infected wounds, with great application potential for the treatment of severe bleeding wounds.

Ternary selenides nanosheets constituting coaxial structural electrode for flexible supercapacitors

For flexible supercapacitors (FSCs), the structural collapse and performance degradation are still bottlenecks that need to be addressed. Herein, Ni-Co selenides (NCS) nanosheets are fabricated into "sponge" grown in situ on flexible conductive nickel-plated carbon cloth (NPCC), constructing the coaxial electrode structure, consisting of NCS nanosheets “sponge layer” (SL), Ni-plated layer (NL) and carbon fiber axis (CFA). The NC0.25S0.5-5/NPCC coaxial electrode shows a high areal capacitance of 6.47 F cm−2 at the 6 mA cm−2 (Hg/HgO reference electrode, 1 M KOH electrolyte) and excellent structural stability with no cracking or fracture after 5000 bending cycles. With the good electronic conductivity, the intermediate NL binds the SL active material and the flexible CFA substrate together to avoid breakage under mechanical deformation. A developed FSC device using the NC0.25S0.5-5/NPCC electrode shows the maximum energy density of 58.4 Wh kg−1. Besides, the excellent flexibility and coaxial structural stability endow the FCS with 90.5% retention of capacitance after 6000 cycles of electrochemical testing and negligible attenuation of electrochemical performance under bending at 180 ° in the last 1000 cycles.

Effects of pomelo peel sponge layer insoluble dietary fibre addition on the properties of the dough and bread

SummaryIn this study, the influences of different proportions (0%, 5%, 10%, 15% and 20% w/w) of pomelo peel sponge layer insoluble dietary fibre (PP‐IDF) on the technological quality, structural character and sensory evaluation of wheat dough and bread were studied. Results showed that the addition of PP‐IDF improved the viscoelasticity of dough and reduced its enthalpy of freezing–thawing. Meanwhile, PP‐IDF significantly improved the quality of bread during storage. Compared with the control, the 7‐day moisture rate of bread containing PP‐IDF increased by 3.50–6.80%, indicating that PP‐IDF retarded the staling process of bread. Moreover, SEM images showed that the bread prepared using PP‐IDF had a more heterogeneous crumb microstructure, and the higher the addition level of PP‐IDF, the larger the void structure. The results of the texture profile analysis indicated that the hardness and chewiness of bread increased with the incorporation of PP‐IDF, suggesting that the addition of PP‐IDF had a negative effect on the texture property of bread. Furthermore, the sensory evaluation of bread was performed, and the taste of the bread was better when PP‐IDF addition content was 5–10%. The results of this study revealed that PP‐IDF had great potential for the development of innovative bread recipes.

Optical coherence tomography for in vivo longitudinal monitoring of artificial dermal scaffold.

Artificial dermal scaffold (ADS) has undergone rapid development and been increasingly used for treating skin wound in clinics due to its good biocompatibility, controllable degradation, and low risk of disease infection. To obtain good treatment efficacy, ADS needs to be monitored longitudinally during the treatment process. For example, scaffold-tissue fit, cell in-growth, vascular regeneration, and scaffold degradation are the key properties to be inspected. However, to date, there are no effective, real-time, and noninvasive techniques to meet the requirement of the scaffold monitoring above. In this study, we propose to use optical coherence tomography (OCT) to monitor ADS in vivo through three-dimensional imaging. A swept source OCT system with a handheld probe was developed for in vivo skin imaging. Moreover, a cell in-growth, vascular regeneration, and scaffold degradation rate (IRDR) was defined with the volume reduction rate of the scaffold's collagen sponge layer. To measure the IRDR, a semiautomatic image segmentation algorithm was designed based on U-Net to segment the collagen sponge layer of the scaffold from OCT images. The results show that the scaffold-tissue fit can be clearly visualized under OCT imaging. The IRDR can be computed based on the volume of the segmented collagen sponge layer. It is observed that the IRDR appeared to a linear function of the time and in addition, the IRDR varied among different skin parts. Overall, it can be concluded that OCT has a good potential to monitor ADS in vivo. This can help guide the clinicians to control the treatment with ADS to improve the therapy.

PDGF and VEGF-releasing bi-layer wound dressing made of sodium tripolyphosphate crosslinked gelatin-sponge layer and a carrageenan nanofiber layer

The use of dressings is one of the most common methods for wound treatment. Since most single-layer dressings cannot mimic the hierarchical structure of the skin well, multi-layer dressings have been considered. In this study, a bilayer dressing was fabricated using a gelatin sponge layer cross-linked with sodium tripolyphosphate (Gel-STPP) and a layer of carrageenan nanofibers containing platelet-rich fibrin (Carr-PRF). Chemical interactions between the two layers were characterized by FTIR, and the microstructure was visualized by SEM. It was found that the presence of Carr-PRF nanofiber layer increased tensile strength by 12.96 % (from 0.216 ± 0.015 to 0.268 ± 0.036 MPa) and elastic modulus by 56.70 % (from 0.388 ± 0.072 to 0.608 ± 0.029 MPa) compared to Gel-STPP sponge. Gel-STPP/Carr-PRF wound dressing had a 45.76 ± 4.18 % degradability after 7 days of immersion in phosphate buffered saline (PBS). PRF-containing bilayer wound dressing was able to sustainably release growth factors over 7 days. The Carr-PRF nanofiber layer coated on Gel-STPP sponge was an ideal environment for adhesion and proliferation of L929 cells. Gel-STPP/Carr-PRF bilayer dressing outperformed the other tested samples in terms of angiogenic potential. Average wound closure was 94.21 ± 2.06 % in Gel-STPP/Carr-PRF dressing treated rats after 14 days, and based on the histopathological and immunohistochemical examinations, the Gel-STPP/Carr-PRF dressing group augmented full-thickness wound healing, keratin layer and skin appendages formation after 14 days.

Behavior of Multilayer Ferrocement Slab Containing Treated Sponge Layer Core

The current study investigates the structural performance of lightweight concrete panels produced using ferrocement (wire-meshed), hybrid (wire-meshed and steel fiber), and sponge-cementitious immersed layers. These panels presented a novel approach to producing a lightweight concrete panel to be used as an alternative to the traditional Jack-arch masonry slab system. The panels were made in dimensions of 600mm length(l), 200mm width (w), and 54mm thickness (h), using locally available sponge materials and super cementitious mortar incorporated with ferrocement layers. To determine the proper thickness of a sponge layer to be used in panel manufacturing, a material characterization was performed. The obtained results from the material characterization indicated a significant reduction in the density compared with the conventional Jack-arch slab system. The sponge core thickness positively affected the developmental compressive strength. For all sponge thickness modes, the density of developed sponging concrete was within the acceptance criteria of lightweight structural concrete. The average density of developing sponge concrete was 15.6 kN/m3, and the average absorption ratio was 14.78 %, while the density of cementitious mortar was 21.96 kN/m3. As for the structural performance of the resulting lightweight concrete panel, the panel with a hybrid layer (incorporating short steel fiber with steel wire mesh) 10mm layer was the best reinforcement method compared with reinforcing with the wire mesh (ferrocement) solely. Furthermore, the findings of this study depicted that the bending moment capacity of the developed lightweight concrete panel was higher than the conventional Jack-arch masonry usually used in traditional residential housing and lower density.

Optimization Study on the Comfort of Human-Seat Coupling System in the Cab of Construction Machinery

The seat of a construction machinery cab is used as the research object. For the current human-seat coupling system comfort research methods and optimization index deficiencies, the seat body pressure comfort and vibration comfort at the same time optimized. Based on the more specialized Toyota 50 percentile dummy model, a human-seat finite element simulation model is established, and the body pressure distribution and vibration response are simulated and calculated. The transverse and longitudinal pressure distributions of the backrest and seat cushion and the pressure map are used to verify the simulation model’s body pressure comfort evaluation indexes. At the same time, the vibration response test is used to verify the vibration comfort evaluation indexes of the simulation model. The test results show that the accuracy of each evaluation index of the established coupling model is greater than 85%, which can provide model support for the subsequent optimization work. In order to improve the comfort of the seat of construction machinery during operation, the hardness of the upper sponge and lower layer sponge is reduced and increased by 10% and 15%, respectively, on the original seat. The body pressure comfort evaluation indexes of the ischium peak pressure, ischium mean pressure, thigh peak pressure and thigh mean pressure are used to evaluate the improved seat. The proposed optimization scheme is to reduce the hardness of the upper sponge and lower layer sponge of the seat cushion by 10% to improve the seat body pressure comfort. Finally, the evaluation indexes of body pressure comfort and vibration comfort are verified by four subjects in an improved seat, and the cushion pressure of different subjects is reduced while the vibration isolation rate is increased, which shows the rationality of the proposed optimization scheme. In addition, the evaluation results of the improved seat are different for subjects of different body sizes, with the most significant improvement for the subject of greater height and weight. The modeling and comfort evaluation methods adopted in the paper can provide a reference for the design and development of the seat.

Engineering Lithiophilic Silver Sponge Integrated with Ion-Conductive PVDF/LiF Protective Layer for Dendrite-Free and High-Performance Lithium Metal Batteries

Although lithium metal anode has attracted much attention as the “Holy Grail” because of its high specific capacity and the lowest reduction potential, its practical applications are largely hindered by the short circuit resulted from the unfavorable growth of lithium dendrites and the unstable interface caused by the parasitic reactions between the highly active lithium metal and the nonaqueous liquid electrolyte. Herein, a multifunctional bilayer structure integrating the spongelike lithiophilic Ag layer and the ion-conductive polyvinylidene difluoride (PVDF)/LiF layer is fabricated for high-performance lithium metal anode. The porous lithiophilic Ag sponge layer provides abundant lithium nucleation sites and deposition space for the uniform growth of lithium, thereby endowing the compact deposition of lithium without the overgrowth of lithium dendrites. The ion-conductive and electronically insulating PVDF/LiF layer improves the lithium-ion transfer and guarantees the interface stability by suppressing the parasitic reactions between the lithium metal and the nonaqueous electrolyte. Moreover, the artificial PVDF/LiF layer can avoid the probability of unfavorable contact between dendrites and the cathode, even though the spongelike Ag layer is “swollen” by the Li metal. Therefore, the PVDF/LiF–Ag@Cu||Li half cell exhibits a more stable average Coulombic efficiency of ∼98.2% and a longer cycle life than Cu||Li and Ag@Cu||Li half cells. Additionally, the symmetric cell of PVDF/LiF–Ag@Li||PVDF/LiF–Ag@Li exhibits a longer cycling time without short circuit and still retains a lower polarization of ∼35 mV for at least 700 h than compared samples. The PVDF/LiF–Ag@Li||LiFePO4 full cell exhibits the longest cycle life, the best rate performance, and the highest capacity retention, especially with a high LiFePO4 mass loading of ∼10 mg cm–2.

Remote internal wave forcing of regional ocean simulations near the U.S. West Coast

Low mode internal waves are able to propagate across ocean basins and modulate ocean dynamics thousands of kilometers away from their generation sites. In this study, the impact of remotely generated internal waves on the internal wave energetics near the U.S. West Coast is investigated with realistically forced regional ocean simulations. At the open boundaries, we impose high-frequency oceanic state variables obtained from a global ocean simulation with realistic atmospheric and astronomical tidal forcing. We use the Discrete Fourier Transform (DFT) technique in separating ingoing and outgoing internal tide energy fluxes at the open boundaries in order to quantify internal tide reflections. Although internal tide reflections are reduced with increasing sponge viscosity and/or sponge layer width, reflection coefficients (λ) can be as high as 73%. In the presence of remote internal waves, the model variance and spatial correlations become more in agreement with both mooring and altimetry datasets. The results confirm that an improved internal wave continuum can be achieved in regional models with remote internal wave forcing at the open boundaries. However, care should be taken to avoid excessive reflections of internal waves from the interior at these boundaries.

Piezoelectric composites from sandwiched polydimethylsiloxane sponges

A novel elastomer-based composite material with enhanced piezoelectric performances is proposed in this paper, which is composed of the top and bottom polytetrafluoroethylene (PTFE) solid films with the middle PTFE nanoparticle–polydimethylsiloxane (PDMS) sponge layer. To enhance the charge retention capability of elastomers, PTFE nanoparticles are introduced to form PTFE–PDMS interfaces, which can trap charges with longevity. Besides, PTFE solid films take on the role of the charge blocking layers to further improve the piezoelectric performances. As a result, the PTFE–PDMS sandwich structure shows the advantages of remarkable sensitivity (1053 pC/N), high stability, and flexibility. After a 6 h of annealing treatment at the temperature of 100 °C, no significant deterioration of the piezoelectric properties can be observed, which reveals the great thermal stability of the sandwich structure. In addition, the sandwich structure can be immersed in water for 24 h without any loss of piezoelectric activity. Finally, the experiment of lighting one LED by hand pressing successfully demonstrates that the sandwich structure has good applicability in the field of energy harvesting. Considering the excellent electrical and mechanical features, the PTFE–PDMS sandwich structure has promising applications in sensing, energy harvesting, and actuation.

Uncovering the Root Causes of Stall Flutter in a Wide Chord Fan Blisk

Flutter was encountered at part speeds in a scaled wide chord fan blisk designed for a civil aeroengine during a rig test when the fan bypass flow was throttled toward its stall boundary. Analysis of the blade tip timing measurement data revealed that the fan blades vibrated at the first flap (1F) mode with nodal diameters of two and three. To facilitate a further rig test and ultimately eliminate the flutter problem, a numerical campaign was launched to help understand the root causes of the flutter. Both the influence coefficient method (ICM) and the traveling wave method (TWM) were employed in the numerical investigation to analyze unsteady flows due to blade vibration, with the intention to corroborate different numerical results and take advantage of each method. To eliminate nonphysical reflections, a sponge layer with an inflated mesh size was used for the extended inlet and outlet regions. Steady flow field and unsteady flow field were examined to relate them to the blade flutter. The influences of vibration frequency, mass flow rate, shock, boundary layer separation and acoustic mode propagation behaviors on the fan flutter stability were also investigated. Particular attention was paid to the acoustic mode propagation behaviors.

Chemical composition, structural and functional properties of insoluble dietary fiber obtained from the Shatian pomelo peel sponge layer using different modification methods

In order to improve the function of Shatian pomelo sponge layer insoluble dietary fiber (IDF), it was modified by high hydrostatic pressure (HHP, 400 MPa, 15 min), cellulose hydrolysis (CH, 0.4% cellulase, 70 min) and alkaline hydrolysis (AH, 1.4% sodium hydroxide solution, 20 min), respectively. Compared with the unmodified IDF, the molecular weight and particle size of the three modified IDFs were both decreased, while their void structure was increased. Specifically, the IDF treated with AH resulted in the smallest particle size (60.63 μm) and a honeycomb-like void structure, which explained why AH-treated IDF showed the strongest glucose and cholesterol adsorption capacities in vitro. The contents of rhamnose, xylose, galactose and galacturonic acid in IDF were significantly increased after HHP treatment (H-IDF). Moreover, H-IDF and CH-treated IDF (C-IDF) exhibited similar capacities for oil-holding and cation-exchange. H-IDF presented the strongest swelling capacity and excellent capacity for cholesterol adsorption. Thus, HHP modified Shatian pomelo peel sponge layer IDF can not only improve the utilization of by-products, but also has potential application value as a novel ingredient in hypolipidemic and hypoglycemic foods products.

Oil-recovery performance of a sponge-covered drum skimmer

Oil spill recovery by means of a rotating drum skimmer covered with a sponge layer was investigated experimentally for a wide range of operating conditions. Tests were conducted on two drums of diameters D = 300 mm and D = 200 mm and lengths L = 300 mm and L = 455 mm, respectively. The examined operating conditions encompassed oil viscosity, rotational speed, slick thickness and centre height above the oil/water interface. The results indicate the superiority of the sponge covered surface in oil recovery over the standard steel surface regardless of the viscosity of oil collected. The sponge-covered drum collected 24% more oil than the plain steel drum, when both were operated under the same conditions. The porous cover improves the skimmer performance due to its ability to absorb oil. The increase in oil slick thickness from 10 to 25 mm led to enhanced recovery rate by 59% in case of sponge-covered drum compared to17.5% with plain steel drum. The study paves the way to applying different types of porous sorbent materials to cover the oleophilic skimmers to achieve higher efficiency and oil recovery rate.

An implicit p‐adaptive discontinuous Galerkin solver for CAA/CFD simulations

Abstract In the last decades flow simulations have become a routine practice in many industrial fields for the aerodynamic and noise prediction. Moreover, the ever increasing interest in simulating off‐design operating conditions promoted the development of high‐fidelity simulation tools to overcome the modeling and accuracy limits of standard industrial codes in predicting turbulent separated flows. The discontinuous Galerkin (DG) method is well suited for this class of simulations, but today DG‐based CFD and CAA (Computational AeroAcoustics) solvers cannot yet reach the computational efficiency of well‐established commercial codes. As a consequence, the present paper aims at exploiting some attractive strategies, such as the adaptation of the elemental polynomial degree (‐adaptation) and of the degree of exactness of quadrature rules, to enhance the computational efficiency of an implicit DG platform for CFD and CAA simulations. Moreover, a sponge layer non‐reflecting boundary treatment has been also implemented for CAA. The predicting capabilities of the method have been assessed on classical CAA and CFD test cases. The proposed adaptive strategy guarantees a significant reduction () of the computational effort for both CFD and CAA simulations, compared to uniform‐order discretizations, while not spoiling the high accuracy requested to an high‐fidelity simulation tool.

Observed and Modeled Mountain Waves from the Surface to the Mesosphere near the Drake Passage

Abstract Four state-of-the-science numerical weather prediction (NWP) models were used to perform mountain wave (MW)-resolving hindcasts over the Drake Passage of a 10-day period in 2010 with numerous observed MW cases. The Integrated Forecast System (IFS) and the Icosahedral Nonhydrostatic (ICON) model were run at Δx ≈ 9 and 13 km globally. The Weather Research and Forecasting (WRF) Model and the Met Office Unified Model (UM) were both configured with a Δx = 3-km regional domain. All domains had tops near 1 Pa (z ≈ 80 km). These deep domains allowed quantitative validation against Atmospheric Infrared Sounder (AIRS) observations, accounting for observation time, viewing geometry, and radiative transfer. All models reproduced observed middle-atmosphere MWs with remarkable skill. Increased horizontal resolution improved validations. Still, all models underrepresented observed MW amplitudes, even after accounting for model effective resolution and instrument noise, suggesting even at Δx ≈ 3-km resolution, small-scale MWs are underresolved and/or overdiffused. MW drag parameterizations are still necessary in NWP models at current operational resolutions of Δx ≈ 10 km. Upper GW sponge layers in the operationally configured models significantly, artificially reduced MW amplitudes in the upper stratosphere and mesosphere. In the IFS, parameterized GW drags partly compensated this deficiency, but still, total drags were ≈6 times smaller than that resolved at Δx ≈ 3 km. Meridionally propagating MWs significantly enhance zonal drag over the Drake Passage. Interestingly, drag associated with meridional fluxes of zonal momentum (i.e., ) were important; not accounting for these terms results in a drag in the wrong direction at and below the polar night jet. Significance Statement This study had three purposes: to quantitatively evaluate how well four state-of-the-science weather models could reproduce observed mountain waves (MWs) in the middle atmosphere, to compare the simulated MWs within the models, and to quantitatively evaluate two MW parameterizations in a widely used climate model. These models reproduced observed MWs with remarkable skill. Still, MW parameterizations are necessary in current Δx ≈ 10-km resolution global weather models. Even Δx ≈ 3-km resolution does not appear to be high enough to represent all momentum-fluxing MW scales. Meridionally propagating MWs can significantly influence zonal winds over the Drake Passage. Parameterizations that handle horizontal propagation may need to consider horizontal fluxes of horizontal momentum in order to get the direction of their forcing correct.