Mixing Intensity Research Articles

Geological Position, Sources, and Age of Mingling Dikes of the Northwestern Margin of the Tuva–Mongolian Massif in Western Sangilen, Southeastern Tuva

Abstract ––The best source of information about the specific features of magmatism in collision zones is the late collisional tectonomagmatic stage, which is associated with the largest volume and diversity of the resulting magmatic associations. In this paper, granitoid and mafic late collisional magmatism is considered using the example of Early Caledonian igneous complexes of Western Sangilen (Tuva–Mongolian massif). Results of geochronological, petrographic, petrogeochemical, and mineralogical studies of the rocks of the Saizyral mingling dike and salic dikes are presented. Approximately ~485 Ma, high-potassium granitoid massifs formed simultaneously with the intrusion and occurrence of a complex of granitoid and mingling dikes. The Saizyral mingling dike resulted from the joint intrusion and mixing of basic and silicic magmas in a low-pressure region within the Erzin shear zone at a middle crust depth level. Interaction of contrasting magmas is comprised of two stages. The first stage occurs during the transport of a contrast mixture and comes down to intensive mechanical mixing and the introduction of LIL and HFS elements, as well as Th and U from granitoids into the mafic rocks. This changes the geochemical characteristics of the mafic rocks. The second stage is when the joint crystallization of magmas is accompanied by gravitational sedimentation of denser mafic magmas and the formation of narrow zones of intermediate composition at the contact of contrasting rocks.

Computational fluid dynamics coupled to biokinetic models: Numerical methodology for microalgae cultivation optimization

Mixing of the algal culture medium in a photobioreactor (PBR) is a crucial factor to enhance microalgae cultivation and production, since it ensures microalgae cells can homogeneously access nutrients and light radiation. Hydrodynamic conditions in an industrially applicable PBR cannot be tested in laboratory cultivation systems since the scale-up methodology is not specified; hence requiring complex tests at a demonstrative scale or the application of mathematical models. In this study, a three-dimensional numerical model of the hydrodynamic conditions in a hybrid horizontal tubular PBR was developed to investigate the mixing of the culture medium under various operating conditions, in order to optimize biomass production in this type of system. The PBR consists of two open tanks connected through sixteen polyethylene transparent tubes, at a demonstrative scale (total volume 11.7 m3). Microalgae cells movement inside the tubes was simulated. Cell trajectory prediction allows to simulate the intensity of mixing of the culture medium. Subsequent coupling with the biokinetic BIO_ALGAE model allows to monitor the influence of hydrodynamic conditions on the distribution of light in the culture medium and the yield of microalgae. The simulations were experimentally validated. The more intense mixing of the culture medium caused by increasing flow rate (Re = 23,700–46,200) allows more frequent exposure of the microalgae cells to the light source, which according to the results obtained can increase the microalgal yield by 14% in the summer cultivation period and by 151% in the winter period.

Process intensification of biodiesel production using pilot-scale continuous multiple baffle reactor with feed distribution

This study aims to enhance biodiesel production through a pilot-scale continuous multiple baffle reactor. This reactor incorporates a baffle array with suitable dimension ratio into the conventional CSTR to create a series of complex flows that increase turbulence and mixing intensity, leading to an increased overall reaction rate. Additionally, this reactor also employed a method of distributing MeOH-KOCH3 solution into 5 streams to enhance mass transfer, reduce catalyst entrapment and ensure the reaction progression throughout the reactor. The investigated variables were the number of baffles, agitation speed, oil to methanol molar ratio, catalyst concentration, and residence time. Ester content of 97.70 wt. % was obtained with residence time of 10 min from single-step transesterification process. This achievement represents 6 times residence time reduction and 75 % reactor cost reduction compared to conventional CSTR with similar reaction conditions and equivalent production capabilities while maintaining simple and highly scalable design of traditional counterparts.

Diffusive–layered convection in Y-shaped continuous-flow microreactor

Efficient and rapid mixing of fluids in continuous-flow microfluidic devices plays an important role in a wide range of applications. Although there are many different methods to enhance mixing in such reactors, the potential of natural convection to mix fluids has been overlooked because of its possible limitations at the microscale. Recent studies have challenged this statement by demonstrating the significance of both gravity-dependent and gravity-independent types of natural convection in improving mixing efficiency. It was shown that inducing double-diffusive convection, Marangoni convection, or Rayleigh–Taylor convection can greatly enhance the mixing of two aqueous solutions in a continuous-flow microreactor. In this study, we experimentally investigate the influence of another type of differential-diffusion instability, known as diffusive–layered convection, on the mixing of two aqueous solutions of chemically inert substances in a Y-shaped continuous-flow microreactor. We consider the scenario when two miscible solutions flow into the main channel through distinct tubes, in which they come into contact and mix, thus causing the onset of diffusive–layered convection. We used two experimental methods, including laser interferometry and dye visualization, to analyse the mixing process. Surprisingly, despite the vigorous convective motion driven by diffusive–layered convection, the intensity of mixing of pumped fluids remains comparable to the scenario when solutions mix only via a diffusion mechanism. We explain this unexpected result by the unique structure of the convective motion, which prevents system homogenization. A comparison with the results previously obtained for double-diffusive convection is performed, and pure diffusive mixing scenarios are implemented.

CARBOHYDRASES – 50 YEARS OF RESEARCH AT THE DEPARTMENT OF CHEMICAL ENZYMOLOGY OF LOMONOSOV MOSCOW STATE UNIVERSITY, HISTORY AND PROSPECTS

The review describes the history of the development of research on carbohydrasеs conducted at the Department of Chemical Enzymology from the mid-1970s to the present. The results concerning the study of the mechanism and kinetics of the processes of enzymatic conversion of cellulose and renewable plant raw materials under the action of a multi-enzyme cellulases complexes; the role of individual components of these complexes - basic (endoglucanases and cellobiohydrolases) and auxiliary enzymes (polysaccharide monooxygenase, β-glucosidase, xylanase) and their synergistic interaction. The features of using reactors of various designs for bioconversion of plant raw materials are described: periodic type, continuous column type, reactor for hydrolysis in a constant electric field, reactor with intensive mixing by ferromagnetic particles in magnetic field. The possibilities of increasing the reactivity of plant raw materials using various pretreatment methods, as well as the influence of the structural and physico-chemical properties of cellulose on the efficiency of its enzymatic conversion are discussed. Data on the creation of highly active strains of microscopic fungi-producers of cellulases and other carbohydrases using methods of induced mutagenesis - Trichoderma (Hypocrea), Penicillium (Talaromyces), Aspergillus, Chrysosporium (Myceliophtora) spp., as well as data on the composition of the enzyme complexes produced by them and the properties of the enzymes forming them are presented. It describes the creation of expression systems based on P. canescens and P. verruculosum and the production of recombinant producer strains with their help, which made it possible to obtain enzyme preparations (EP) that ensure high efficiency of bioconversion processes of plant raw materials, as well as to create producers of a wide range of carbohydrases for practical use in various fields of industry and agriculture. A number of industrially important EP obtained using the P. verruculosum expression system are currently being produced at the Agroferment LLC plant.

Influence of mixing conditions on coagulant recovery efficiency and quality

Abstract In this work, the influence of mixing conditions on aluminium recovery from alum sludge and on the recovered coagulant (RC) quality was investigated using acidic treatment. The response surface methodology with a Face Centred Design was used to evaluate the effects of velocity gradient and mixing time on aluminium recovery efficiency, and on the chemical oxygen demand (COD), total suspended solids (TSS) and total phosphorus contents of the RC. No significant effects of both mixing intensity and mixing time on aluminium recovery efficiency were observed; however, these factors significantly affected the quality of the RC in terms of COD, TSS and total phosphorus. The higher velocity gradient increased COD and TSS and the longer mixing time increased phosphorus and TSS in the RC. Operational conditions velocity gradient = 100 s−1 and mixing time = 5 minutes) for aluminium recovery were suggested on economic basis. At these conditions, the RC presented the lowest values of TSS and total phosphorus (100 mg L−1 and 7.0 mg P L−1, respectively), and the following other characteristics: 1,001 mg Al L−1; 384 mg Fe L−1; 1100 mg COD L−1.

On the Optimal Choice of Type of Combustion Chamber for the Initiation of Gas Detonation

A numerical simulation of continuous gas detonation in the combustion chamber based on the Navier-Stokes equations, taking into account turbulence and diffusion of substances, is carried out. A comparative analysis of the efficiency of detonation combustion of fuel depending on the geometric parameters of the chambers is performed. Three possible camera types are considered. Fuel and oxidizer were fed separately into the chambers through nozzles at a certain angle to the chamber surface. The detonation process was largely determined by the intensity of the turbulent mixing of reagents (hydrogen and oxygen). Calculations show that the type of camera with a flat radial geometry is the most optimal to establish a stable detonation regime.

Granular Carbon Adsorbent Based on Soot and Synthetic Pitch

A method for producing granular carbon adsorbent by stirring a suspension of soot in a solution of naphthalene (in heptane) in the presence of sulfuric acid was proposed. Experimental research together with mathematical processing of the results made it possible to propose a mechanism for the formation of spherical carbon granules from soot and naphthalene: in the course of intense mixing in the presence of concentrated sulfuric acid, a binder material was formed from naphthalene, and it was adsorbed on the surface of soot particles. The resulting particles with a thin layer of binding material on their surface stuck together in the field of centrifugal forces to form larger particles, which ultimately acquired a spherical shape and had a size of up to 5 mm. A comparison of the resulting carbon granules (from soot and synthetic pitch) with granules preparedby mixing soot and petroleum pitch showed that the proposed adsorbent had specific surface area and mechanical strength greater by factors of 1.5–2.

A multi-stage enhanced flocculation reactor for the treatment of simulated shale gas hydraulic fracturing flowback fluid: Effect of aspect ratios for the intense mixing section

Flocculation is a significant process in treating shale gas hydraulic fracturing flowback fluids. To achieve a high removal rate of pollutant, a range of multi-stage enhanced flocculation reactors that incorporated sequential intense, moderate, and weak mixing sections along the flow direction were devised, in which the aspect ratios (ARs) in the intense mixing section were varied. The results of the computer simulation indicated that the reactor with AR of 3.5 exhibited a gradual decrease in velocity and energy along the flow direction, and the flow field distribution is highly uniform and symmetrical. The generated flow field promoted the formation of small flocs in the intense mixing section and facilitated the collision of small flocs in the moderate mixing section, while preventing the fragmentation of flocs in the weak mixing section, therefore resulting in the generation of large and compact flocs. Moreover, the generated flocs demonstrated a good resistance to shear and oscillation, facilitating their separation from the simulated flowback fluids. The obtained reactor achieved remarkable removal efficiencies of 80.15 % for COD and 89.06 % for turbidity. Furthermore, when treating bentonite suspension, the multi-stage flocculation reactor achieved a turbidity removal rate of 99.34 % with a processing time of only 2.38 min and a settling time of just 20 min. This demonstrated the broad applicability of this reactor to various types of wastewater. This work provides valuable insights into the design of efficient flocculation reactors by integrating multiple mixing intensities within a reactor.

Effects of Mixing at Pore Intersections on Large‐Scale Dissolution Patterns and Solute Transport

AbstractThe flow‐induced dissolution of porous rocks governs many important subsurface processes and applications. Solute mixing, which determines pore‐scale concentration fields, is a key process that affects dissolution. Despite its importance, the effects of pore‐scale mixing on large‐scale dissolution patterns have not been investigated. Here, we use a pore network model to elucidate the mixing effects on macroscopic dissolution patterns and solute transport. We consider two mixing rules at pore intersections that represent two end members in terms of the mixing intensity. We observe that the mixing effect on dissolution is the strongest at moderate Damköhler number, when the reactive and advective time scales are comparable. This is the regime where wormholes spontaneously appear. Incomplete mixing is shown to enhance flow focusing at the tips of the dissolution channels, which results in thinner wormholes and shorter breakthrough times. These effects on passive solute transport are evident independent of initial network heterogeneity.

Diffusion instability in three-component gas mixtures containing greenhouse gas

The work discusses the influence of pressure and composition of a ternary gas mixture on the possibility of the occurrence of convective instability under isothermal conditions due to differences in the diffusion abilities of the components. The change in “diffusion – concentration gravitational convection” regimes in isothermal ternary gas mixtures CH4 + R12 – Ar, N2 + R12 – n-C4H10 was experimentally studied. It has been shown that instability in the systems under study can occur at a certain content of the component with the highest molecular weight in the mixture. Its further increment in the initial composition of the mixture leads to the emergence of convective flows and an increase in the intensity of mixing. Experiments have confirmed that pressure also determines the transition from a diffusion state to a convective one. A growth in pressure contributes to an increase in the intensity of convective mixing. For a flat vertical channel at certain values of composition and pressure, nonmonotonic concentration distributions causing a significantly nonlinear density distribution with an extremum, which is unusual from the point of view of diffusion, were recorded. The regions of stable and unstable behavior of the system for a wide range of mixture composition and pressure are studied in terms of Rayleigh numbers. The location of the areas where diffusion and instability occur is compared with the results of the experiments.

Desmoid-type fibromatosis of neck masquerading as nerve sheath tumors: two case reports

BackgroundDesmoid fibromatosis (DF) is an atypical, non-malignant tumor known for its distinctive feature of exhibiting an intermediate biological behavior that falls between benign fibrous lesions and fibrosarcoma. The article aimed to outline the imaging characteristics of desmoid fibromatosis and distinguish it from its similar counterpart, nerve sheath tumors.ResultsHere, we present two cases of desmoid fibromatosis whose imaging findings mimic nerve sheath tumors. The patients presented with neck swelling and radiating pain. Both cases were biopsy-proven. Imaging features characteristic of these lesions include elongated shape, split-fat sign, and fascial tail sign with mixed signal intensity on T1WIs and T2WIs depending upon the collagen content of the lesion.ConclusionsMRI is the best diagnostic modality for differentiating fibromatosis from nerve sheath tumors. Surgery continues to be the primary approach for treating these growths, but in some cases, chemoradiation is employed to achieve improved control rates. The presence of intralesional low-intensity bands in T2WIs is a characteristic feature of fibromatosis. Given its local aggressiveness and propensity for recurrence, the use of multiple imaging modalities is essential for providing informed guidance on outcomes and treatment strategies.

A 3D homogeneous microreactor with high mixing intensity at wide Re range for MOF preparation and POCT application

Most microreactors can only work under high Re or extremely low Re conditions to obtain enough mixing efficiency, the inefficient reaction intensity undoubtedly limits its application scenarios. In this study, a novel 3D homogeneous microreactor (3D-HM) was reported that demonstrate a strong mixing intensity over a wide range of Re conditions. The 3D geometries of shunt and lateral secondary flow structure were optimized in details, and then were added to the Zigzag mixing channel to promote mixing index (MI) (over 94 % from Re = 0–10, and more than 98 % for Re > 10). Compared with the traditional T-shaped, Split and Recombine micromixer, a shorter mixing distance (Lmix) and mixing time (τmix) were needed to realize fully mixing. The 3D-HM was used for the preparation of Zeolitic imidazolate framework (ZIF-8), the particle size, yield and drug loading capacity of ZIF-8 prepared using the 3D-HM under a milder Re conditions were better than those prepared by traditional and existing microfluidic methods under a harsh Re conditions. The promotion to diffusion mixing with 3D-HM channel was then verified using the enzymatic catalytic reaction driven by syringe pump at low Re and capillary pump, respectively. Enzyme and substrates in the laminar flow in the 3D-HM are more likely to bind each other than that in the T-shaped diffusion mixing. In addition, the laminar diffusion mixing process was scaled up by microfluidic channel design, so that the results of enzymic catalytic reaction was visualized for Point-of-care Testing (POCT) application. The MI, Lmix and τmix directly determine the homogeneous microreaction intensity. The proposal of the 3D-HM may provide more possibilities for the application of micromixing-based reactors.

Impact of critical eddy diffusivity on seasonal bloom dynamics of Phytoplankton in a global set of aquatic environments

The intensity of eddy diffusivity and the spatial average of water velocity at the depths of the water column in oceans and lakes play a fundamental role in phytoplankton production and phytoplankton and zooplankton biomass, and community composition. The critical depth and intensity of turbulent mixing within the water column profoundly affect phytoplankton biomass, which depends on the sinking characteristic of planktonic algal species. We propose an Nutrient-Phytoplankton-Zooplankton (NPZ) model in 3D space with light and nutrient-limited growth in a micro-scale ecological study. To incorporate micro-scale observation of phytoplankton intermittency in bloom mechanism in stationary as well as oceanic turbulent flows, a moment closure method has been applied in this study. Experimental observations imply that an increase in turbulence is sometimes ecologically advantageous for non-motile planktonic algae. How do we ensure whether there will be a bloom cycle or whether there can be any bloom at all when the existing phytoplankton group is buoyant, heavier, motile, or non-motile? To address these questions, we have explored the effects of critical depth, the intensity of eddy diffusivity, spatial average of water velocity, on the concentration as well as horizontal and vertical distribution of phytoplankton and zooplankton biomass using a mathematical model and moment closure technique. We quantify a critical threshold value of eddy diffusivity and the spatial average of water velocity and observe the corresponding changes in the phytoplankton bloom dynamics. Our results highlight the importance of eddy diffusivity and the spatial average of water velocity on seasonal bloom dynamics and also mimic different real-life bloom scenarios in Mikawa Bay (Japan), Tokyo Bay (Japan), Arakawa River (Japan), the Baltic Sea, the North Atlantic Ocean, Gulf Alaska, the North Arabian Sea, the Cantabrian Sea, Lake Nieuwe Meer (Netherlands) and several shallower lakes.

Validity Test of an Alternative Method of Quantitative Pain Assessment (MAPKN) in Assessing Intensity of Nociceptive Pain, Mixed Pain, and Neuropathic Pain

Pain is a health problem phenomenon that most often brings patients to see a doctor. Pain intensity is the most often domain which assessed in clinical and research settings. Loeser suggests that four elements need to be considered when evaluating patients with pain. Based on the biopsychosocial approach and the concept of pain from Loeser, a pain assessment was made and called "Alternative Method of Quantitative Pain Assessment (MAPKN)". This study was conducted on 415 pain patients consisting of 163 nociceptive pain, 119 mixed pain, and 133 neuropathic pain. In the nociceptive pain group, MAPKN showed sensitivity 92.59%, specificity 96.43%, AUC 0,959 and a p value <0.001. In the mixed pain group, MAPKN showed sensitivity 98.17%, specificity 80.00%, AUC 0,836 and a p -value of 0.001. In the neuropathic pain group, MAPKN showed sensitivity 92.06%, specificity of 85.71%, AUC 0,951 and a p<0.001. The AUC value of 0.959 (96%) indicates that the diagnostic value of the MAPKN score in assessing pain intensity in the nociceptive pain group is excellent (>90%-100%). AUC value of 0.836 (83%) indicates that the diagnostic value of the MAPKN score in assessing pain intensity in the mixed pain group is good (> 80%-90%). The AUC value of 0.951 (95%) indicates that the diagnostic value of the MAPKN score in assessing pain intensity in the neuropathic pain group is excellent (>90%-100%). This is in accordance with research conducted by Eka Pranata 2004 that MAPKN has strong discriminant validity in assessing pain intensity. MAPKN is valid and has excellent diagnostic value in assessing nociceptive and neuropathic pain intensity, MAPKN is valid and has good diagnostic value in assessing mixed pain intensity.

Improved XFEM for 3D interfacial crack modeling

The conventional extended finite element method (XFEM) usually suffers from the crack tip enrichment for removing the blending elements. This may be inconvenient when treating the three dimensional (3D) and curved crack modeling since the crack tip enrichment is usually defined in the local coordinate system depending on the crack front. To avoid these shortcomings of the XFEM, an improved enrichment scheme is proposed for the 3D interfacial crack modeling. The proposed enrichment scheme removes the crack tip enrichment and two weight functions are introduced to capture the strong and weak discontinuities in the element including the crack front. The new enrichment scheme has advantages for the 3D curved interfacial cracks since all the enrichment functions are defined in the global system and it is unnecessary to introduce additional coordinate systems. Several benchmark problems including the mixed mode stress intensity factors (SIFs), anti-plane load and curved cracks are analyzed by the proposed method with the local refinement technology. Numerical results demonstrate that the proposed method can obtain accurate 3D energy release rate and SIFs. In addition, the proposed method enhances the applications of XFEM and has the potential abilities to the multiple-fields coupling and interfacial crack growth phenomena due to the fact that compatible enrichment functions are utilized.

Residence time distribution of an offshore floating photobioreactor under hydrodynamic sloshing effect

Sloshing is the movement of fluid in a partially filled vessel subjected to external motions. Although sloshing causes intense forces and instability to floating structures, the internal motion of liquid caused by external forces might be useful for devices that require mixing. For offshore floating photobioreactors, sloshing induced by external ocean wave forces are desirable, as the movement of liquid is able to bring about mixing and mass transfer for the nutrients and gas in the microalgae culture. The objective of this study is to investigate the correlation between the regular wave-induced sloshing of different motions (surge, heave, and pitch) on the mixing behaviour of the novel offshore floating photobioreactor designed to utilize the ocean surface waves for the effects of mixing. To determine the residence time distribution (RTD) of the stagnant volume of the photobioreactor, dissolved solids were injected into the system. The concentration of dissolved solids was measured using a total dissolve solid (TDS) sensor. The mixing caused by sloshing motion had the highest intensity during pitching motion. A homogenous solution was formed just after 65.9 s for the filling ratio of 30 %, with the rotation angle of 8 degrees and frequency of 0.21 Hz. Thus, wave-induced sloshing is able to generate intense mixing to the medium during pitching motion but still has non-ideal behaviours, such as bypass and dead zones during horizontal and vertical motion.

The flame structure and combustion dynamics in a steam diluted H2/Air micromix flame

The OH* chemiluminescence is used to investigate experimentally the effects of nozzle diameter (d), steam dilution ratio (D) and equivalence ratio (φ) on flame structure and combustion dynamics in a steam diluted H2/air micromix burner. Two flame types, anchored and lifted, are found. The OH* signal for the anchored flame primarily presents in flame shear layer zone (SLZ), while that for the lifted flame mainly appears in the flame central recirculation zone (CRZ) and flame tail zone (FTZ). The increase of the velocity of hydrogen (as the D decreasing or the φ increasing) would change anchored flame to lifted flame. The Power Spectral Density (PSD) analysis shows that changing from anchored to lifted flame would result a high OH* fluctuation frequency, which shows the same trend as the decrease of d. The Dynamic Mode Decomposition (DMD) analysis shows that the distribution of dominant mode is similar to the distribution of OH* signal. The SLZ is the primary oscillation zone for anchored flame and the CRZ for lifted flame. The anchored flame is more stabler comparing to the lifted one, and the lifted flame should be avoided in practical burners. Besides, the high mixing intensity of fuel and oxidizer is beneficial to the stability of micromix flame.

Evaluating the aeration efficiency of hydraulic flume on photo-oxidative disinfection of wastewater

Photosensitized oxidation has been considered to offer better disinfection mechanism under natural sunlight and the efficiency of its inactivation pathway depends on the concentration of dissolving oxygen, the solar irradiance, and the reactive nature of the liquid. This study aimed to evaluate the hydraulic mixer's aeration performance during photo-oxidation treatment. A hydraulic jump was created to aerate the sewage prior to its passage into a reactor, and the amount of dissolved oxygen generated was measured. The effect of mixing intensity on sunlight inactivation of faecal coliforms in a reactor was investigated for 60 min using velocity gradients of 520 s−1, 640 s−1, 720 s−1 and 960 s−1 produced under flow rates of 3 L min−1, 5 L min−1 and 7 L min−1 and 10 L min−1 respectively. The photo-oxidation kinetics of faecal coliform contained in settled and raw sewage samples were also studied under two dark control tests (static and dynamic tests) and a light test. The system achieved a 2.0–2.34 log reduction of faecal coliforms and dissolved oxygen was within the range of 1.9 mg L−1 - 3.0 mg L−1. In the dynamic control test, the inactivation rate constant of bacteria indicated a reduction of 1.11 log (92%) for settled sewage and 1.0 log (90%) for raw sewage. The coliform inactivation rate constant, due to the combined effect of turbulent mixing speed and dark inactivation rate constant, was 2.3 h−1, and the solar irradiance inactivation rate constant was 2.4 h−1. These results have demonstrated that induced aeration is an economically friendly approach to enhance wastewater treatment in developing nations with long sunshine hours.

Effects of subgrid‐scale turbulence parametrization on the representation of clear‐air turbulence using kilometre‐ to hectometre‐scale numerical simulations

A turbulence event arising in a jet exit region above the Belgium–Luxembourg area, determined from airliner in‐situ measurements, is reproduced using the meteorological models Application de la Recherche à l'Opérationnel à Méso‐Echelle (AROME) and Meso‐NH at horizontal resolutions of 1.3 km and 260 m. The behaviour of the subgrid turbulence scheme at 1.3 km and its sensitivity to various parameters are analysed, with results being evaluated using measurements. An increase of the vertical resolution around the tropopause levels with m is shown to greatly enhance the turbulence representation. The use of a non‐local formulation of the mixing length in the current parametrization at 1.3 km allows reproduction of a turbulence signal in agreement with the observations. On the contrary, the use of a fully three‐dimensional formulation has no impact on the simulation at this resolution (1.3 km). Using the 260 m runs, this turbulence event is linked to hydrodynamical wind shear instabilities characterized by horizontal wavelength of 4.5 km, sub‐resolved at the operational resolution. At these small grid‐size scales, turbulence evolution and equation budgets reflect an equilibrium between dynamical production and turbulence dissipation, and highlight the importance of horizontal gradients. Subgrid turbulence intensities are assessed to be underestimated by the current parametrization at 1.3 km when compared with this high‐resolution reference simulation. Finally, different tests on the turbulence parametrization illustrate a transfer between resolved and subgrid kinetic energy in the model. This transfer stresses the importance of a trade‐off between mixing intensity and the representation of wind at resolved scales for the upper troposphere.