Total Heat Flux Research Articles

Comparative analysis of material for flat & dome top piston for SI engine using ansys

Compared to other areas of the IC engine, the working condition of piston attracts the most attention rather than any part in IC engine due to its complexity. Pistons have undergone many significant material and topographic changes since their first industrial introduction to overcome these working conditions. It is being said that electric vehicles will take over the world, but until the Lithium-ion battery remains, there will always be a shortage for batteries. Taking this as an assumption and the fact that carbon neutral fuel is currently in development, our goal is to make the piston lighter and more durable to make it future ready. In this research article, our objective is to substantiate and analyze the stress distribution of the piston with various [1] piston crown designs, namely, [1] flat top and dome top; integrated with various synthetic and alloy materials, namely, Titanium alloy, [2] Aluminum alloy, [3] Super magnesium, and [4] 3D Graphene. [5] Static Structural and Steady state thermal analysis is performed on these pistons using ANSYS R2 2022 software, while designing is performed on AutoCAD 2020 software. This article presents and analyses [5] thermal stress analysis and damages due to pressure application. Results are displayed comparing based on [5,6,7] total deformation, Von-mises strain, Von-mises stress, strain energy, normal elastic strain, normal stress, total heat flux and directional heat flux. Result is concluded by comparing to find the most preferable material for the piston in an engine. The preference is given based upon weight reduction, strength, and future scope of the material.

Understanding the Duration of Solar and Stellar Flares at Various Wavelengths

Recent irradiance measurements from numerous heliophysics and astrophysics missions including Solar Dynamics Observatory (SDO), GOES, Kepler, TESS, Chandra, the X-ray Multi-Mirror Mission, and NICER have provided critical input into understanding the physics of the most powerful transient events on the Sun and magnetically active stars:solar and stellar flares. The light curves of flare events from the Sun and stars show remarkably similar shapes, typically with a sharp rise and protracted decay phase. The duration of solar and stellar flares has been found to be correlated with the intensity of the event in some wavelengths, such as white light, but not in other wavelengths, such as soft X-rays, but it is not evident why this is the case. In this study, we use a radiative hydrodynamics code to examine factors affecting the duration of flare emission at various wavelengths. The duration of a light curve depends on the temperature of the plasma, the height in the atmosphere at which the emission forms, and the relative importance of cooling due to radiation, thermal conduction, and enthalpy flux. We find that there is a clear distinction between emission that forms low in the atmosphere and responds directly to heating, and emission that forms in the corona, indirectly responding to heating-induced chromospheric evaporation, a facet of the Neupert effect. We discuss the implications of our results for a wide range of flare energies.

The Contribution of Plasma Sheet Bubbles to Stormtime Ring Current Buildup and Evolution of Its Energy Composition

AbstractThe formation of the stormtime ring current is a result of the inward transport and energization of plasma sheet ions. Previous studies have demonstrated that a significant fraction of the total inward plasma sheet transport takes place in the form of bursty bulk flows, known theoretically as flux tube entropy‐depleted “bubbles.” However, it remains an open question to what extent bubbles contribute to the buildup of the stormtime ring current. Using the Multiscale Atmosphere Geospace Environment Model, we present a case study of the 17 March 2013 storm, including a quantitative analysis of the contribution of plasma transported by bubbles to the ring current. We show that bubbles are responsible for at least 50% of the plasma energy enhancement within 6 RE during this strong geomagnetic storm. The bubbles that penetrate within 6 RE transport energy primarily in the form of enthalpy flux, followed by Poynting flux and relatively little as bulk kinetic flux. Return flows can transport outwards a significant fraction of the plasma energy being transported by inward flows, and therefore must be considered when quantifying the net contribution of bubbles to the energy buildup. Data‐model comparison with proton intensities observed by the Van Allen Probes show that the model accurately reproduces both the bulk and spectral properties of the stormtime ring current. The evolution of the ring current energy spectra throughout the modeled storm is driven by both inward transport of an evolving plasma sheet population and by charge exchange with Earth's geocorona.

Identifying some regularities of the heat transfer in the welded joint of SUS304 pipe using a numerical approach

In this study, an investigation into the impact of heat transmission in the welded junction of SUS304 pipe has been carried out with the use of a numerical method. An investigation was carried out by employing ANSYS’s static structural tools in conjunction with the software package’s thermal transient analysis. Based on the heat flow on the welding point, where the temperature reaches 507 °C within 200 mm of the end of the welded pipe, an examination into the efficiency of heat transfer has been carried out. This analysis was based on the heat flow on the welding point. As the total heat flux approaches 7.02e6 W∙m–2, studies have been conducted on the topic. There have been three types of directional heat flux measurements made (X, Y, and Z), with the numerical findings indicating that the X direction produces the most variable heat flow readings. These checks were performed in a variety of settings. These were chosen as the correct paths to go since they led directly to the source of the warmth. whereas the Z-axis permits the minimum amount of heat flow throughout the board. The damaged area identified on the trees that were still standing was factored into the calculation. To calculate the amount of residual stress, the Von Mises stress was applied repeatedly during the whole procedure. This tactic ended up being employed. Due to the tension caused by the pipe’s increased bending radius, the piece of pipe located 200 mm from the pipe’s distal end is the most vulnerable. The value was calculated to be 2.49e6 Pa when the temperature was increased to 500 °C.

Numerical Simulation of Lithium-ion Battery Cooling Techniques for Electric Vehicles

Various strategies were developed for battery cooling including air cooling, liquid cooling, fin cooling, phase change material cooling (PCM), and heat pipes. The objective of this study was to identify an appropriate cooling technique for lithium-ion batteries utilized in electric vehicles. A three-dimensional unsteady numerical model was developed using ANSYS software to conduct simulations to assess the cooling efficiency of each approach. The numerical results indicate that the air-cooling technique yielded a peak temperature of 32.928 °C and a maximum total heat flow of 11456 W/m2. The fin cooling technique had a peak total heat flow of 0.014476 W/m2 and reached a maximum temperature of 35.17 °C. The liquid cooling technique exhibited a peak temperature of 31.773 °C and a maximum total heat flux of 10642 W/m2. Additionally, a changed battery pack was planned with extra air outlets to upgrade the convection cycle of the air-cooling technique. Based on the numerical findings, the modified battery pack for air-cooling technique resulted in a peak temperature of 31.214 °C and a maximum total heat flow of 12272 W/m2. PCM and heat pipe method had a maximum temperature of 54.85 °C and a maximum total heat flow of 554.69 W/m2. According to the results obtained, the liquid cooling method demonstrated the lowest maximum temperature. The simulations indicate that this approach offers the most effective thermal management, with a maximum temperature value of 31.773 °C.

Thermal energy simulation of the building with heating tube embedded in the wall in the presence of different PCM materials

A large part of energy consumption around the world is spent on buildings. Improving and optimizing the thermal performance of buildings can reduce energy consumption. Phase change materials inside an envelope can act as a latent thermal energy storage tank and also prevent energy loss. In the present study, we have investigated the effects of adding PCM inside the wall of buildings, and a tube for heating is embedded inside the wall. The performance of the system has been evaluated based on computational fluid dynamics simulation in Open Foam software. PIMPLE algorithm and finite volume method were used to solve the governing equations. Three different arrangements of tubes are considered at the upper, middle, and bottom of the wall introduced as UTA, MTA, and BTA, respectively. Furthermore, it is assumed that the heat flux is in the range of solar heat flux that enters the system from the embedded tube. Three different tube arrangements, three heat fluxes, and two different types of PCMs have been investigated in this study to find the best integration of the system. The simulation results revealed that for Lauric acid, by increasing the heat flux from 200 to 400 Wm2, the melting time decreases from 9 to 2 h. Also, for Paraffin the melting start time reaches 2.5h from 10 h. Also, Lauric acid can store or discharge thermal energy for the long term. The highest percentage of stored energy is related to Lauric acid, which saves 13.8 % of the total input heat flux as latent energy and Paraffin stores up to 11.8 % of latent heat energy.

Design and Analysis of Brake Drum using Finite Element Analysis

Because of the need for safety, braking performance has become a very important factor for automotive manufacturers and passengers. Despite all the stresses experienced by the drum brake doesn’t damage the drum due to high tensile strength but the drum may fail under fatigue loading. The critical region of concentrated stress is determined, and appropriate modifications are being made to improve it. The distribution of stress and the heat dissipation obtained from the result of the analysis are employed as input for the failure region. The findings of stress and thermal analysis are crucial for improving the component design at the first stage of development. The objectives of this study are to modify and improve the circumferential strength and heat dissipation and to optimize the design of the drum brake with simulation using Finite Element Analysis. The simulation was run on the initial model and modified on its to make it better. it shows that 27.33% decrease in maximum von Mises stress. Thermal analysis for heat flux on the material will show the ability of heat dissipation. Overall, It has been determined that aluminium alloy is the optimum material for drum brake design in terms of total heat flux.

Roles of catalysts’ porous media feature and catalytic conversion effect on the performance of plate-fin heat exchangers in hydrogen liquefaction

Ortho-para hydrogen conversion is essential for hydrogen liquefaction and filling catalysts inside channels of plate-fin heat exchangers (PFHXs) is the most efficient method of conversion. However, the roles of the catalysts’ porous media feature and catalytic conversion effect on the performance of PFHXs filled with ortho-para hydrogen conversion catalysts are barely discussed. Three cases, i.e., Case A (normal PFHX), Case B (PFHX filled with non-catalytic particles acting as porous media), and Case C (PFHX filled with catalysts), are numerically studied and compared to illustrate the influence of filled ortho-para hydrogen conversion catalysts on the performance of the PFHX. The thermal-hydraulic performance coefficient (ηTHP) is defined to illustrate the combined performance of thermal (j factor) and hydraulic performance (f factor), and the conversion efficiency (ηCON) is defined to evaluate the conversion performance of the heat exchanger. The comparison between Case A and Case B shows that the particles acting as porous media restrain the hydraulic performance of normal PFHX while enhance the thermal performance. In comparison with Case B, as the ortho-para hydrogen conversion effect is considered in Case C, j factor is reduced by 1.8 % and the flow resistance is increased by 8.9 %, denoting that the conversion heat leads to deterioration of heat transfer and hydraulic performance. Parametric analyses show that, when the Reynolds number rises from 214.0 to 1569.1, ηTHP and ηCON in Case C increase by 304.9 % and 10.2 % respectively, implying that the Reynolds number is quite influential to the performance. Beside, the proportion of conversion heat in the total heat flux rises along the flow direction and tends to level off, reaching about 45 %.

Measurements of heat flux components due to charged and non-charged particles in DIII-D divertor near and under detachment

Surfacing Eroding Thermocouples (SETC) have been used to provide high spatial and temporal resolution heat flux measurement in DIII-D. SETCs were first tested in the lower divertor of DIII-D using the Divertor Material Evaluation System (DiMES), then an array of SETCS was permanently installed in the upper SAS-VW divertor for studying the heat flux mitigation in closed divertor geometry. SETCs proved that inducing divertor detachment with various methods is an effective way to reduce the peak heat flux at the divertor targets. In the investigated discharges the heat flux is reduced to less than 30% under detachment compared to attached conditions. A new method of using the combination of recessed SETC and flush SETC was demonstrated to be able to measure the heat flux from volumetric radiation and the charge exchange neutrals. It was observed that the magnitude of the heat flux from radiation and charge exchange neutrals increased during the process of detachment. While 30% of the total incident heat flux is attributable to the volumetric radiation and the charge exchange neutrals in the fully detached divertor condition with B×∇B drift into the divertor, it could reach more than 60% with B×∇B drift away from the divertor.

Thermal conductivity of Fe-bearing bridgmanite and post-perovskite: Implications for the heat flux from the core

The thermal conductivity of the lowermost mantle controls the energy transfer from the core to the mantle, and provides insight into the thermal history, evolution, and magnetic field of the Earth. Bridgmanite (Brg) and post-perovskite (PPv) are the most abundant minerals in the lowermost mantle. However, their thermal conductivities, as well as the impact of Fe impurities, are highly controversial. In this study, the thermal conductivities of Fe-free and Fe-bearing Brg and PPv at high pressure and temperature were predicted, through a combination of non-equilibrium molecular dynamics and machine learning potential (MLP) trained with data from first-principles calculations. The thermal conductivities of Fe-free Brg and PPv are in agreement with those calculated by the Green-Kubo method based on the MLP. We found that the presence of 12.5 mol% Fe in the lowermost mantle decreases the thermal conductivities of Brg and PPv by ∼10% and ∼14%, respectively. Furthermore, the phase transition from Brg to PPv increases the thermal conductivity of pyrolite by ∼22%. Incorporating the distribution of minerals, temperature, and iron content obtained through the inversion based on mineral elasticity and seismic tomography models, a global heat flow with substantial lateral variation at the core-mantle boundary was reported. The total heat flux from the core was found to be 7.1 ± 0.5 TW, implying a geologically young inner core of 0.75 ± 0.35 Ga.

Doubling of surface oceanic meridional heat transport by non-symmetry of mesoscale eddies

Oceanic transport of heat by ubiquitous mesoscale eddies plays a critical role in regulating climate variability and redistributing excess heat absorbed by ocean under global warming. Eddies have long been simplified as axisymmetric vortices and their influence on heat transport remains unclear. Here, we combine satellite and drifter data and show that oceanic mesoscale eddies are asymmetric and directionally-dependent, and are controlled by their self-sustaining nature and their dynamical environment. Both the direction and amplitude of eddy-induced he.at fluxes are significantly influenced by eddy’s asymmetry and directional dependence. When the eddy velocity field is decomposed into asymmetric and symmetric components, the eddy kinetic energy exhibits a nearly equal partition between these two components. The total eddy-induced meridional heat flux similarly doubles the heat flux induced by the symmetric components, highlighting the crucial contribution of eddy asymmetry on the magnitude of eddy-induced oceanic heat transport.

Strengthening cold wakes lead to decreasing trend of tropical cyclone rainfall rates relative to background environmental rainfall rates

Tropical cyclone (TC) rainfall is an important component of global precipitation. Based on a 22-year satellite-based record of observed precipitation from 1998 to 2019, we find that composite rainfall rates averaged within 500 km of TCs have increased. However, the background precipitation rate in the TC-affected regions has also increased. Therefore we find, by subtracting the background increase in precipitation rate from the TC precipitation composite, that TC precipitation rates--relative to the background--have decreased, and that TC-related extreme precipitation rates near the TC center have also decreased. Besides TC intensity and environmental sea surface temperature, the TC-induced sea surface cooling, typically formed like a cold wake feature, is indicated to be a potentially important contributor to TC rainfall changes. The cold wake diminishes the upward transport of surface enthalpy flux and leads to a decrease of moisture in the boundary layer, being unfavorable for the rainfall. The relative decreasing rainfall trend of TCs to the background is therefore attributed to the strengthening sea surface cooling induced by TCs. The TC-ocean interaction is suggested to be fully resolved in state-of-the-art global and regional climate models in order to improve TC rainfall simulations and projections.

Impact of Assimilating Satellite and Glider Observations on Hurricane Isaias (2020) Forecast Using Marine JEDI

Abstract Realistic ocean initial conditions are essential for coupled hurricane forecasts. This study focuses on the impact of assimilating high-resolution ocean observations for initialization of the Modular Ocean Model (MOM6) in a coupled configuration with the Hurricane Analysis and Forecast System (HAFS). Based on the Joint Effort for Data Assimilation Integration (JEDI) framework, numerical experiments were performed for the Hurricane Isaias (2020) case, a category-1 hurricane, with use of underwater glider datasets and satellite observations. Assimilation of ocean glider data together with satellite observations provides opportunity to further advance understanding of ocean conditions and air–sea interactions in coupled model initialization and hurricane forecast systems. This comprehensive data assimilation approach has led to a more accurate prediction of the salinity-induced barrier layer thickness that suppresses vertical mixing and sea surface temperature cooling during the storm. Increased barrier layer thickness enhances ocean enthalpy flux into the lower atmosphere and potentially increases tropical cyclone intensity. Assimilation of satellite observations demonstrates improvement in Hurricane Isaias’s intensity forecast. Assimilating glider observations with broad spatial and temporal coverage along Isaias’s track in addition to satellite observations further increase Isaias’s intensity forecast. Overall, this case study demonstrates the importance of assimilating comprehensive marine observations to a more robust ocean and hurricane forecast under a unified JEDI–HAFS hurricane forecast system. Significance Statement This is the first comprehensive study of marine observations’ impact on hurricane forecast using marine JEDI. This study found that assimilating satellite observations increases upper-ocean stratification during the prestorm period of Isaias. Assimilating preprocessed observations from six gliders increases salinity-induced upper ocean barrier layer thickness, which reduces sea surface temperature cooling and increases enthalpy flux during the storm. This mechanism eventually enhances hurricane intensity forecast. Overall, this study demonstrates a positive impact of assimilating comprehensive marine observations to a successful ocean and hurricane forecast under a unified JEDI–HAFS hurricane forecast system.

The association between childhood adiposity in northeast China and anthropogenic heat flux: A new insight into the comprehensive impact of human activities.

Anthropogenic heat has been reported to have significant health impacts, but research on its association with childhood adiposity is still lacking. In this study, we matched the 2008-2012 average anthropogenic heat flux, as simulated by a grid estimation model using inventory methods, with questionnaire and measurement data of 49,938 children randomly recruited from seven cities in Northeast China in 2012. After adjusting for social demographic and behavioral factors, we used generalized linear mixed-effect models to assess the association between anthropogenic heat flux and adiposity among children. We also examined the effect modification of various social demographic and behavioral confounders. We found that each 10W/m2 increase in total anthropogenic heat flux and that from the industry source was associated with an increase of 5.82% (95% CI=0.84%-11.05%) and 6.62% (95% CI=0.87%-12.70%) in the odds of childhood adiposity. Similarly, the excess rate of adiposity among children were 5.26% (95% CI=-1.33%-12.29%) and 8.51% (95% CI=2.24%-15.17%) per 1W/m2 increase in the anthropogenic heat flux from transportation and buildings, and was 7.94% (95% CI=2.28%-13.91%) per 0.001W/m2 increase in the anthropogenic heat flux from human metabolism. We also found generally greater effect estimates among female children and children who were exposed to passive smoking during pregnancy, born by caesarean section, non-breastfed/mixed-fed, or lived within 20m adjacent to the main road. The potential deleterious effect of anthropogenic heat exposure on adiposity among children may make it a new but major threat to be targeted by future mitigation strategies.

Aftbody Heat Flux Measurements During Mars 2020 Entry

The Mars Entry, Descent, and Landing Instrumentation 2 (MEDLI2) sensor suite on the Mars 2020 mission included two total heat flux sensors and one radiometer on the backshell to directly measure the aftbody aerothermal environments during entry into the Martian atmosphere. All three sensors successfully returned aftbody entry heating measurements. Comparisons between the total heat flux sensor measurements and predictions by NASA simulation tools (DPLR/NEQAIR) show excellent agreement and provide confidence in the models. The radiometer measured significant radiative heating, but compared to the model predictions the signal was attenuated by 48% at the end of the entry heat pulse. The loss of signal is attributed to blockage by thermal protection system (TPS) ablation product deposits on the radiometer window. Ground-based testing in the NASA Ames arcjet facilities was conducted to understand the impact of ablation product deposits on the measured radiometer signal. A discussion of the test results, how flight-like the test conditions were, and future work to further characterize the effect of TPS ablation product deposits on the radiometer performance are presented. In addition to measuring the entry heat pulse, all three sensors were sensitive enough to measure solar radiation during cruise, the radiometer measured solar flux during the entry heat pulse, and the leeside total heat flux sensor picked up the descent reaction control system firings.

A novel cooling capacity prediction model for open-type cooling radiant ceiling

Open-type cooling radiant ceiling panel systems (O-CRCP) have a higher cooling capacity, but their cooling capacity can only be calculated roughly according to the model of the closed-type cooling radiant ceiling panel systems (C-CRCP), which may cause economic and energy waste. This study aims to develop a novel cooling capacity prediction model for O-CRCP considering the impact of panel size, layout, and installation position. The experimental results revealed that the heat flux of the O-CRCP was 49%–64% greater than that of the C-CRCP. A detailed analysis of the simulation results shows that the natural convective heat transfer is the main factor for the cooling capacity enhancement which basically determines the trend of the total heat flux varying with various factors. Based on the simulation results, a novel cooling capacity prediction model for O-CRCP was developed using a multi-regression method. It was evaluated in an actual room with O-CRCP, and the predicted cooling capacity curve showed good agreement with the measured values, the relative error ranged from 5.78% to 9.72% with an average of 7.47%, which is acceptable for engineering applications. The proposed model can provide support and guidance for designers and engineers in selecting and arranging O-CRCP in real applications.

Regimes of Convective Self-Aggregation in Convection-Permitting Beta-Plane Simulations

Abstract The spontaneous self-aggregation (SA) of convection in idealized model experiments highlights the importance of interactions between tropical convection and the surrounding environment. The authors have shown that SA fundamentally changes with the background rotation in previous f-plane simulations, in terms of both the resulting forms of organized convection and the relative roles of the physical feedbacks driving them. This study considers the dependence of SA on rotation in one large domain on the β plane, introducing an additional layer of complexity. Simulations are performed with uniform thermal forcing and explicit convection. Focuses include statistical and structural analysis of the convective modes, process-oriented diagnostics of how they develop, and resulting mean states. Two regimes of SA emerge within the first 15 days, separated by a critical zone where f is analogous to 10°–15° latitude. Organized convection at near-equatorial values of f primarily consists of convectively coupled Kelvin waves. Wind speed–surface enthalpy flux feedbacks are the dominant process driving moisture variability early on, then clear-sky shortwave radiative feedbacks are strongest in wave maintenance. In contrast, at higher f, numerous tropical cyclones develop and coexist, dominated by surface flux and longwave processes. Tropical cyclogenesis is most pronounced at intermediate f (analogous to 25°–40°), but are longer-lived at higher f. The resulting modes of SA at low f differ between these β-plane simulations (convectively coupled waves) and prior f-plane simulations (weak tropical cyclones or nonrotating clusters). Otherwise, these results provide further evidence for the changing roles of radiative, surface flux, and advective processes in influencing SA as f changes, as found in our previous study. Significance Statement In model simulations, convection often self-organizes due to interactions with its surrounding environment. These interactions are relevant in the real-world organization of rainfall and clouds, and may thus be useful to understand for improved prediction of tropical weather and climate. Previous work using a set of simple model experiments with constant Coriolis force showed that at different latitudes, different processes dominate, and different types of organized convection result. This study verifies that finding using a more complex and realistic model, where the Coriolis force varies within the domain to resemble different latitudes. Specifically, the convection here self-organizes into atmospheric waves (periodic disturbances) at low latitudes, and tropical cyclones at high latitudes.

Marine heatwave as a supercharger for the strongest typhoon in the East China Sea

Due to the cold water temperatures, the East China Sea (ECS) is usually unfavorable for typhoon development. Recently, in a rare event, Typhoon Bavi (2020) reached major typhoon status and became the strongest typhoon in the ECS in the past decade. Based on in situ observations and model simulations, we discover that this typhoon is fueled by a marine heatwave, which creates a very warm ocean condition with sea surface temperature (SST) exceeding 30 °C. Also, because of suppressed typhoon-induced SST cooling caused by the shallow water depth (41 m) and strong salinity stratification (river runoff) within the ECS, the SST beneath the typhoon remains relatively high and enhances the total heat flux for the typhoon. More interestingly, due to the fair weather ahead of the typhoon, we find that the rapid development of this marine heatwave is likely, in part, attributed to the typhoon itself. As the risks from typhoons and marine heatwaves are heightening under climate change, this study provides important insights into the interaction between typhoons and marine heatwaves.

Effect of wind turbulences on the burning of a rockrose hedge

With climate change, complex fire scenarios at Wildland Urban Interfaces (WUI) have become a growing concern for authorities worldwide. Such scenarios involve unfavorable wind conditions, which greatly increase the fire spread near communities and makes the intervention of firefighters even more complex. To design effective fire safety regulations to protect communities, it is important to have a clear understanding of the role of wind in the burning of vegetation to help identify the vectors of fire spread within the defensible zone. In this context, this paper attempts to relate the properties of the flames generated by the burning of a reconstructed rockrose hedge to the atmospheric wind turbulence using four field-scale experiments. The experimental setup includes 3 visible cameras to record the flame geometry, extracted by post-processing; 3 pairs of radiant and total heat fluxes to record the heat fluxes downstream of the hedge, and an anemometer to measure the wind speed and direction. The results show that the wind at the experimental site is composed of wall-bounded turbulent structures coupled with strong and short intermittent events such as gusts. Regarding the fire, the four replicates show similarities in phase durations and dynamics, but revealed dependencies on Reynolds number and turbulent kinetic energy when averaging over the fully developed flame phase. In addition, a slight flapping motion of the ensemble flame was observed and associated with wave numbers of the order of the turbulent cascade in the kinetic energy power spectra. Finally, the analysis of wind and fire intermittencies revealed that strong and short wind events generate large fluctuations of flame geometry and received heat fluxes that increase with the characteristic time of the event considered.

Ocean mixing during Hurricane Ida (2021): the impact of a freshwater barrier layer

Tropical cyclones are +ne of the costliest and deadliest natural disasters globally, and impacts are currently expected to worsen with a changing climate. Hurricane Ida (2021) made landfall as a category 4 storm on the US Gulf coast after intensifying over a Loop Current eddy and a freshwater barrier layer. This freshwater layer extended from the coast to the open ocean waters south of the shelf-break of the northern Gulf of Mexico (GoM). An autonomous underwater glider sampled this ocean feature ahead of Hurricane Ida operated through a partnership between NOAA, Navy, and academic institutions. In this study we evaluate hurricane upper ocean metrics ahead of and during the storm as well as carry out 1-D shear driven mixed layer model simulations to investigate the sensitivity of the upper ocean mixing to a barrier layer during Ida’s intensification period. In our simulations we find that the freshwater barrier layer inhibited cooling by as much as 57% and resulted in enhanced enthalpy flux to the atmosphere by as much as 11% and an increase in dynamic potential intensity (DPI) of 5 m s-1 (~9.72 knots) in the 16 hours leading up to landfall. This highlights the utility of new ocean observing systems in identifying localized ocean features that may impact storm intensity ahead of landfall. It also emphasizes the northern Gulf of Mexico and the associated Mississippi River plume as a region and feature where the details of upper ocean metrics need to be carefully considered ahead of landfalling storms.