Role Of Turbulence Research Articles

Wide-binary eccentricity distribution in young star clusters: dependence on the binary separation and mass

ABSTRACT We study the wide-binary eccentricity (e) distribution in young star clusters and the role of turbulence in setting the form of the e distribution using magnetohydrodynamical simulations of star cluster formation. The simulations incorporate gravity, turbulence, magnetic fields, protostellar heating, and jets/outflows. We find that (1) simulations that employ purely compressive turbulence driving produce binaries with a superthermal e distribution [$\alpha \gt 1$ in $p(e) \propto e^\alpha$], while simulations with purely solenoidal driving or natural mixture of driving modes produce subthermal/thermal distributions ($\alpha \le$ 1), (2) the e distribution over the full range of binary separations in our simulations is set at the early stages of the star cluster formation process, (3) while binaries (separation of $r_{\mathrm{pair}} \le 1000\, \mathrm{AU}$) have subthermal to thermal e distributions ($\alpha \sim 0.8$), wide binaries ($r_{\mathrm{pair}} \gt 1000\, \mathrm{AU}$) have a superthermal distribution ($\alpha \sim 1.8$), and (4) low-mass binary systems (system masses of $M_{\mathrm{sys}} \le 0.8\, \mathrm{M_\odot }$) have a highly superthermal distribution ($\alpha \sim 2.4$), whereas high-mass systems ($M_{\mathrm{sys}} \gt 0.8\, \mathrm{M_\odot }$) exhibit a subthermal/thermal distribution ($\alpha \sim 0.8$). The binary eccentricity distribution is often modelled as a thermal distribution. However, our results suggest that the e distribution depends on the range of separation of the sampled binaries, which agrees with the findings from recent Gaia observations. We conclude that the dependence of the e distribution on the binary separation and mass is linked to the binary formation mechanism governed by the turbulent properties of the parent cloud.

Role of turbulence in Dinophysis spp. growth, feeding, and toxin leakage in culture

Dinophysis, a mixotrophic dinoflagellate that is known to prey on the ciliate Mesodinium rubrum, and retain its chloroplasts, is responsible for diarrhetic shellfish poisoning (DSP) in humans and has been identified on all U.S. coasts. Monocultures of Dinophysis have been used to investigate the growth of Dinophysis species in response to variations in environmental conditions, however, little is known about the roles of system stability (turbulence) and mixotrophy in the growth and toxicity of Dinophysis species in the U.S.. To begin to address this gap in knowledge, culturing experiments were conducted with three species (four strains) of Dinophysis, that included predator-prey co-incubation (Dinophysis spp.+ M. rubrum) and prey-only (M. rubrum) flasks. Cultures were investigated for effects of low or high turbulence on Dinophysis spp. growth, feeding, and amounts of intra- and extracellular toxins: okadaic acid and derivatives (diarrhetic shellfish toxins, DSTs) and pectenotoxins (PTXs). Turbulence did not have a measurable effect on the rates of ingestion of M. rubrum prey by Dinophysis spp. for any of the four strains, however, effects on growth and particulate and dissolved toxins were observed. High turbulence (ε = 10−2 m2s−3) significantly slowed growth of both D. acuminata and D. ovum relative to still controls, but significantly stimulated growth of the D. caudata strain. Increasing turbulence also resulted in significantly higher intracellular toxin content in D. acuminata cultures (DSTs and PTXs), but significantly reduced intracellular toxin content (PTXs) in those of D. caudata. An increase in turbulence appeared to promote toxin leakage, as D. ovum had significantly more extracellular DSTs found in the medium under high turbulence when compared to the still control. Overall, significant responses to turbulence were observed, whereby the three strains from the “Dinophysis acuminata complex” displayed a stress response to turbulence, i.e., decreasing growth, increasing intracellular toxin content and/or increasing toxin leakage, while the D. caudata strain had an opposite response, appearing stimulated by, or more tolerant of, high turbulence.

Enhanced Energy Conversion by Turbulence in Collisionless Magnetic Reconnection

Abstract Magnetic reconnection and turbulence are two of the most significant mechanisms for energy dissipation in collisionless plasma. The role of turbulence in magnetic reconnection poses an outstanding problem in astrophysics and plasma physics. It is still unclear whether turbulence can modify the reconnection process by enhancing the reconnection rate or energy conversion rate. In this study, utilizing unprecedented high-resolution data obtained from the Magnetospheric Multiscale spacecraft, we provide direct evidence that turbulence plays a vital role in promoting energy conversion during reconnection. We reached this conclusion by comparing magnetotail reconnection events with similar inflow Alfvén speed and plasma β but varying amplitudes of turbulence. The disparity in energy conversion was attributed to the strength of turbulence. Stronger turbulence generates more coherent structures with smaller spatial scales, which are pivotal contributors to energy conversion during reconnection. However, we find that turbulence has negligible impact on particle heating, but it does affect the ion bulk kinetic energy in these two events. These findings significantly advance our understanding of the relationship between turbulence and reconnection in astrophysical plasmas.

Role of turbulence in ozone chemistry: Segregation effect implicated from multiscale modeling over Hong Kong

By influencing the mixing of reactive species in the atmosphere, turbulence affects the rates at which chemical species react, specifically in the planetary boundary layer. To analyze the turbulent segregation effect on the atmospheric ozone photochemistry, coupled meso-to micro-scale simulations are performed over Hong Kong, a polluted megacity. The comparison of the ozone production rates between the mesoscale model and the large-eddy simulations (LES) indicates that the resolved turbulent processes inhibit the mixing of the reactants, and thereby slow down the reaction rate between NO and O3, resulting in a smaller net O3 production when represented by a LES simulation. The calculated segregation intensities show clear correlations with the emission distribution, revealing that the segregation effect is significant in urban areas with inhomogeneous pollution sources, including traffic emissions. The evolution of the eddy structure plays a significant role in the diurnal variation of the segregation intensity. Applying the obtained segregation intensities to the mesoscale output, the NO–O3 reaction rate decreases with results closer to those provided by the LES model. This confirms the importance of the segregation effect on fast chemical reactions and provides insights into the parameterization of the segregation effect in mesoscale models, which do not resolve turbulent eddies.

Oceanic Frontal Turbulence

Abstract Upper-ocean turbulence results from a complex set of interactions between submesoscale turbulence and local boundary layer processes. The interaction between larger-scale currents and turbulent fluctuations is two-way: large-scale shearing motions generate turbulence, and the resulting coherent turbulent fluxes of momentum and buoyancy feed back onto the larger flow. Here we examine the evolution and role of turbulence in the intensification, instability, arrest, and decay (i.e., the life cycle) of a dense filament undergoing frontogenesis in the upper-ocean boundary layer, i.e., cold filament frontogenesis (CFF). This phenomenon is examined in large-eddy simulations (LES) with resolved turbulent motions in large horizontal domains using 109 grid points. The boundary layer turbulence is generated by surface buoyancy loss (cooling flux) and is allowed to freely interact with an initially imposed cold filament, and the evolution is followed through the frontal life cycle. Two control parameters are explored: the initial frontal strength M2 = ∂xb and the surface flux . The former is more consequent: initially weaker fronts sharpen more slowly and become arrested at a later time with a larger width. This reflects a competition between the frontogenetic rate induced by the secondary circulation associated with vertical momentum mixing by the turbulence and the instability rate for the along-filament shear flow. The frontal turbulence is energized by the shear production of the latter, is nonlocally transported away from the primary production zone at the filament centerline, and cascades to dissipation in a broad region surrounding the filament. The turbulent momentum fluxes arresting the frontogenesis are supported across a wide range of horizontal scales.

The role of turbulence in high-mass star formation: Subsonic and transonic turbulence are ubiquitously found at early stages

Context. Traditionally, supersonic turbulence is considered to be one of the most likely mechanisms slowing the gravitational collapse in dense clumps, thereby enabling the formation of massive stars. However, several recent studies have raised differing points of view based on observations carried out with sufficiently high spatial and spectral resolution. These studies call for a re-evaluation of the role turbulence plays in massive star-forming regions. Aims. Our aim is to study the gas properties, especially the turbulence, in a sample of massive star-forming regions with sufficient spatial and spectral resolution, which can both resolve the core fragmentation and the thermal line width. Methods. We observed NH3 metastable lines with the Very Large Array (VLA) to assess the intrinsic turbulence. Results. Analysis of the turbulence distribution histogram for 32 identified NH3 cores reveals the presence of three distinct components. Furthermore, our results suggest that (1) sub- and transonic turbulence is a prevalent (21 of 32) feature of massive star-forming regions and those cold regions are at early evolutionary stage. This investigation indicates that turbulence alone is insufficient to provide the necessary internal pressure required for massive star formation, necessitating further exploration of alternative candidates; and (2) studies of seven multi-core systems indicate that the cores within each system mainly share similar gas properties and masses. However, two of the systems are characterized by the presence of exceptionally cold and dense cores that are situated at the spatial center of each system. Our findings support the hub-filament model as an explanation for this observed distribution.

Safety factor influence on the edge E × B velocity establishment in tokamak plasmas

This study is motivated by experiments on Tore Supra and WEST tokamaks where a deepening of the E × B velocity—governed by the radial electric field Er —near the edge is observed when the safety factor decreases in L-mode plasmas. Flux-driven global simulations of ion temperature gradient turbulence recover qualitatively the trend observed in the experiments, i.e. the E × B velocity increases when decreasing the safety factor. From these simulations, multiple clues point out the role of turbulence in the establishment of the radial electric field even though the turbulent intensity increases with the safety factor. The proposed mechanism to elucidate this phenomenon, backed up by a reduced model, is that the damping of the poloidal flow, governed by the neoclassical friction, increases more strongly with the safety factor than the turbulent drive for Er , due to the (r,θ) component of the Reynolds stress.

The role of turbulence in the deposition of intrinsically buoyant MPs

Intrinsically floating microplastics (MP) such as polyethene (PE) or polypropylene (PP) are among the most common MPs found in aquatic sediments. There must hence be mechanisms that cause lighter-than-water MPs to deposit despite them being buoyant. How these MPs end up in the sediment bed is only partly understood. This study explores how turbulence in the water can affect the vertical movement of buoyant MP and bring them in contact with the bed. The deposition of PE (995 kg m−3) in slow-flowing water (average flow velocities of 1.85 and 4.17 cm s−1) was measured by tracking them and analyzing their motion in an open, rectangular, glass-sided flume. Flow characteristics in terms of turbulent kinetic energy and shear velocity were measured by particle image velocimetry. Experiments were conducted at a water depth of 27 cm and at various hydraulic conditions created by adjusting inflow speeds and using different bed materials: medium gravel, fine gravel, medium sand, cohesive sediment, and glass. The results showed that the vertical velocity of the MPs in the turbulent flow regimes varied over 4 orders of magnitude from their predicted rising velocity in quiescent water (laminar flow). Turbulence mixing resulted in distribution throughout the water column with a substantial quantity consistently subject to downward vertical transport, which in turn increased the chance of the PE particles encountering the bed and potentially getting immobilized. This work provides a plausible explanation and further experimental validation for the concept of mixing induced transfer of MPs from the water surface to the sediments of shallow waters.

CCN activation in homogeneous isotropic turbulence: Response to particle characteristics and environmental conditions

Direct Numerical Simulation (DNS) of turbulent cloud parcels are presented where particles evolve in response to the local values in supersaturation (s) led by turbulent fluctuations. A pseudo-spectral DNS is modified to incorporate aerosol particles and Cloud Condensation Nuclei (CCN) activation applying a droplet growth equation based on κ-Köhler theory that works for the whole range of warm cloud particles, from un-activated deliquesced aerosol particles to activated cloud droplets, that grow by condensation. The Lagrangian microphysics applied ensures that each particle experiences a supersaturation (fluctuations added to the mean) corresponding to its near-particle gas phase surroundings, which differs from the uniform parcel view where an average value of supersaturation, s¯, is applied to every particle in the domain. A non-turbulent Lagrangian parcel model with similar mean thermodynamics and CCN properties is compared with turbulent DNS parcels of varying fluctuation intensities to distinguish the impact of turbulence on CCN activation. It is shown that, in a given distribution, a subset of aerosols respond to fluctuations rather than the mean thermodynamics allowing particles of similar dry size to co-exist as un-activated haze particles as well as cloud droplets. The cloud microphysical properties are analysed in a series of DNS experiments with contrasting thermodynamic and aerosol properties. DNS results agrees with the general understanding of aerosol activation and cloud droplets evolution in response to various background conditions such as pristine and polluted aerosol distributions, composition of CCN with respect to organic - inorganic components and magnitude of vertical velocity. DNS considers turbulence-microphysics interactions in such problems providing additional knowledge on the role of turbulence in clouds. It is argued that incorporating turbulent fluctuations in simulating the CCN activation and droplet growth is well reasoned and a constructive way forward.

Role of turbulence and winding in the development of large-scale, strong magnetic fields in long-lived remnants of binary neutron star mergers

Role of turbulence and winding in the development of large-scale, strong magnetic fields in long-lived remnants of binary neutron star mergers

Turbulence spreading and its effects on the edge flows and turbulence during sawtooth cycles in the J-TEXT tokamak plasmas

Turbulence spreading and its effects on the edge flows and turbulence during sawtooth cycles in the J-TEXT tokamak plasmas are presented. These experiments were performed by Langmuir probe array and electron cyclotron emission. This study aims to understand the rapid transport phenomenon and the role of turbulence in driving flows. Beyond the mixing radius, the turbulence pulse moves faster than the sawtooth heat pulses. The results confirm the existence of turbulence spreading during sawtooth cycles. As the turbulence and heat pulses propagate to the edge, the edge turbulence, radial electric fields, pressures, and geodesic acoustic modes are all enhanced. Hysteresis relationships between the intensities of the turbulence and the radial electric fields are observed. The radial electric field lags behind the turbulence, and its intensity increases/decreases almost linearly with the increase/decrease in the turbulence intensity. The observation suggests that the edge flows are driven dominantly by turbulence during sawtooth cycles. The weakening/enhancement of the edge flows accompanies the increase/decrease in the ion collision rates during sawtooth cycles.

Comparison of Spring Wind Gusts in the Eastern Part of the Tibetan Plateau and along the Coast: The Role of Turbulence

Wind gusts are sudden, brief increases in wind speed that have important implications for wind power generation, building design, aviation and marine safety. However, wind gusts in the Plateau and coastal plain are very different. In this paper, the gust characteristics are explored and compared at two sites in the same latitude—Xining, a city in the eastern Tibetan Plateau, and Qingdao, a city in the coast in China—using Doppler lidar data. The results indicate that the wind gusts in Xining are more intense and occur at a higher height than those in Qingdao. Though mean winds and turbulence significantly influence gusts, the turbulence intensity is responsible for the differences in gust, and high turbulence in the eastern part of the Tibetan Plateau is inferred. These results provide observational evidence for wind gusts over the complex terrain of the Tibetan Plateau and are useful for studying their impact on important aspects, such as flight safety.

Electrification in turbulent channel flows of liquid dielectrics

Electrification of wall-bounded flows of liquid dielectrics occurs via the transport of electric-charge carriers (ions) from the electrical double layer at a liquid–solid interface to the bulk of the flow. This phenomenon is currently not well understood, but it has been proposed that flow turbulence plays a major role on it. However, conclusive studies about the role of turbulence and the underpinning mechanisms of flow electrification are still lacking. In this paper, we report on direct numerical simulations (DNS) of electrification in turbulent channel flow of liquid dielectrics and for friction Reynolds numbers ranging from 150 to 210. Our simulations confirm that turbulence increases dramatically the amount of charge transported in the bulk of the flow. Also, the electrification rate increases with the turbulence intensity. Nonetheless, ionic diffusion does not influence the electrification process, due to the large value of the ionic Schmidt number. Our simulations further predict that, upon electrification, the charge-density profile consists of three zones. In the first one, adjacent to the wall, the dominant mechanism is ionic diffusion, whereas in the second one, the dominant mechanisms are convective and conductive currents. In the third zone, the bulk of the flow, the charge density remains almost constant. Also, according to the budget of the charge-density variance, molecular transport counterbalances molecular dissipation in the first zone, and production counterbalances turbulent transport in the second one. Finally, we provide a closed-form expression for the mean charge-density profile based on the gradient assumption, which agrees well with our DNS results.

The role of turbulence in the characteristic velocity and length of rocket combustors

High-fidelity direct numerical simulations are conducted to investigate combustion performance in high-pressure methane-oxygen diffusion flames with different inlet turbulence. The results are post-processed to investigate the influence of turbulence on characteristic velocity and length. It is found that despite the eminent fuel-rich non-premixed configuration of the flame, a substantial amount of heat release takes place in premixed lean conditions. It is found that the occurrence of this phenomenon increases with the turbulent kinetic energy due to the mixing enhancement driven by the greater strain rate. The greater prevalence of lean combustion is beneficial for combustion performance near injection but detrimental for the completion of chemical reactions at downstream positions. It is found that excessive upstream oxygen consumption is responsible for this result. With more prevalence of lean combustion, oxygen is depleted sooner, and alternative reaction paths through carbon dioxide reduction are necessary to finalize the burning process. Moreover, it is observed that lower entry turbulence is beneficial for the downstream mixing intensity since it enhances the generation of radial velocity shear and flame-generated turbulence. The opposing effects of turbulence upstream and downstream determine the existence of optimal turbulence characteristics providing minimum characteristic length while achieving complete burnout. The combustion chamber volume savings associated with this optimal configuration are in the order of 50%.

Convective and Turbulent Motions in Nonprecipitating Cu. Part III: Characteristics of Turbulence Motions

Abstract Velocity field in a nonprecipitating Cu under BOMEX conditions, simulated by SAM with 10-m resolution and spectral bin microphysics is separated into the convective part and the turbulent part, using a wavelet filtering. In Part II of the study properties of convective motions of this Cu were investigated. Here in Part III of the study, the parameters of cloud turbulence are calculated in the cloud updraft zone at different stages of cloud development. The main points of this study are (i) application of a fine-scale LES model of a single convective cloud allowed a direct estimation of turbulence parameters using the resolved flow in the cloud and (ii) the separation of the resolved flow into the turbulence flow and the nonturbulence flow allowed us to estimate different turbulent parameters with sufficient statistical accuracy. We calculated height and time dependences of the main turbulent parameters such as turbulence kinetic energy (TKE), spectra of TKE, dissipation rate, and the turbulent coefficient. It was found that the main source of turbulence in the cloud is buoyancy whose contribution is described by the buoyancy production term (BPT). The shear production term (SPT) increases with height and reaches its maximum near cloud top, and so does BPT. In agreement with the behavior of BPT and SPT, turbulence in the lower cloud part (below the inversion level) is weak and hardly affects the processes of mixing and entrainment. The fact that BPT is larger than SPT determines many properties of cloud turbulence. For instance, the turbulence is nonisotropic, so the vertical component of TKE is substantially larger than the horizontal components. Another consequence of the fact that BPT is larger than STP manifests itself in the finding that the turbulence spectrum largely obeys the −11/5 Bolgiano–Obukhov scaling. The classical Kolmogorov −5/3 scaling dominates for the low part of a cloud largely at the dissolving stage of cloud evolution. Using the spectra obtained we evaluated an “effective” dissipation rate which increases with height from nearly zero at cloud base up to 20 cm2 s−3 near cloud top. The coefficient of turbulent diffusion was found to increase with height and ranged from 5 m2 s−1 near cloud base to 25 m2 s−1 near cloud top. The possible role of turbulence in the process of lateral entrainment and mixing is discussed. Significance Statement 1) This study investigates the turbulent structure of Cu using a 10-m-resolution LES model with spectral bin microphysics, 2) the main source of turbulence is buoyancy, 3) turbulence in cumulus clouds (Cu) is nonisotropic, 4) turbulence reaches maximum intensity near cloud top, 5) turbulence spectrum obeys largely the −11/5 Bolgiano–Obukhov scaling, and 6) the main turbulent parameters are evaluated.

The market turbulence, entrepreneurial marketing and marketing performance: An empirical study of tuna fillets SME's industry in Southeast Sulawesi, Indonesia

This study examines market turbulence's role in moderating the relationship between entrepreneurial marketing and marketing performance in tuna fillets SME industries in Southeast Sulawesi, Indonesia. The research was conducted in two cities in Southeast Sulawesi Province, Indonesia - Kendari City and Baubau City. The population of this research is all of the managers or owners of the fillets tuna industry in both cities, which amount to 118 industries, 73 tuna fillet SMEs industry in Kendari City, and 45 in Baubau City. Data were collected based on census technique from 118 industries that became respondents. Respondents are the managers or owners of the tuna fillet industry. Next, the data were analyzed using Partial Least Square (PLS) analysis to test the research hypothesis. The study found that entrepreneurial marketing practices applied by managers or owners of the tuna fillets SME's industries in Southeast Sulawesi could improve marketing performance. The study results also indicate that the dimensions of entrepreneurial marketing partially affect marketing performance. Market turbulence has a positive moderating role in the relationship between entrepreneurial marketing and marketing performance.

Large-eddy simulations of the ice-shelf–ocean boundary layer near the ice front of Nansen Ice Shelf, Antarctica

Abstract. Ice melting beneath Antarctic ice shelves is caused by heat transfer through the ice-shelf–ocean boundary layer (IOBL). However, our understanding of the fluid dynamics and thermohaline physics of the IOBL flow is poor. In this study, we utilize a large-eddy simulation (LES) model to investigate ocean dynamics and the role of turbulence within the IOBL flow near the ice front. To simulate the varying turbulence intensities, we imposed different theoretical profiles of the velocity. Far-field ocean conditions for the melting at the ice-shelf base and freezing at the sea surface were derived based on in situ observations of temperature and salinity near the ice front of the Nansen Ice Shelf. In terms of overturning features near the ice front, we validated the LES simulation results by comparing them with the in situ observational data. In the comparison of the velocity profiles to shipborne lowered acoustic Doppler current profiler (LADCP) data, the LES-derived strength of the overturning cells is similar to that obtained from the observational data. Moreover, the vertical distribution of the simulated temperature and salinity, which were mainly determined by the positively buoyant meltwater and sea-ice formation, was also comparable to that of the observations. We conclude that the IOBL flow near the ice front and its contribution to the ocean dynamics can be realistically resolved using our proposed method. Based on validated 3D-LES results, we revealed that the main forces of ocean dynamics near the ice front are driven by positively buoyant meltwater, concentrated salinity at the sea surface, and outflowing momentum of the sub-ice-shelf plume. Moreover, in the strong-turbulence case, distinct features such as a higher basal melt rate (0.153 m yr−1), weak upwelling of the positively buoyant ice-shelf water, and a higher sea-ice formation were observed, suggesting a relatively high speed current within the IOBL because of highly turbulent mixing. The findings of this study will contribute toward a deeper understanding of the complex IOBL-flow physics and its impact on the ocean dynamics near the ice front.

The Role of Turbulence in Fueling the Subsurface Chlorophyll Maximum in Tidally Dominated Shelf Seas

AbstractGlider observations show a subsurface chlorophyll maximum (SCM) at the base of the seasonal pycnocline in the North Sea during stable summer conditions. A colocated peak in the dissipation rate of turbulent kinetic energy suggests the presence of active turbulence that potentially generates a nutrient flux to fuel the SCM. A one‐dimensional turbulence closure model is used to investigate the dynamics behind this local maximum in turbulent dissipation at the base of the pycnocline (PCB) as well as its associated nutrient fluxes. Based on a number of increasingly idealized forcing setups of the model, we are able to draw the following conclusions: (a) only turbulence generated inside the stratified PCB is able to entrain a tracer (e.g., nutrients) from the bottom mixed layer into the SCM region; (b) surface wind forcing only plays a secondary role during stable summer conditions; (c) interfacial shear from the tide accounts for the majority of turbulence production at the PCB; (d) in stable summer conditions, the strength of the turbulent diapycnal fluxes at the PCB is set by the strength of the anticyclonic component of the tidal currents.

Deep modeling of plasma and neutral fluctuations from gas puff turbulence imaging.

The role of turbulence in setting boundary plasma conditions is presently a key uncertainty in projecting to fusion energy reactors. To robustly diagnose edge turbulence, we develop and demonstrate a technique to translate brightness measurements of HeI line radiation into local plasma fluctuations via a novel integrated deep learning framework that combines neutral transport physics and collisional radiative theory for the 33D - 23P transition in atomic helium with unbounded correlation constraints between the electron density and temperature. The tenets for experimental validity are reviewed, illustrating that this turbulence analysis for ionized gases is transferable to both magnetized and unmagnetized environments with arbitrary geometries. Based on fast camera data on the Alcator C-Mod tokamak, we present the first two-dimensional time-dependent experimental measurements of the turbulent electron density, electron temperature, and neutral density, revealing shadowing effects in a fusion plasma using a single spectral line.

Ignition and flame stabilization of n‐dodecane turbulent premixed flames under Spray A thermochemical conditions

The role of turbulence on two-stage ignition and subsequent flame stabilization at compression ignition engine conditions is assessed by performing direct numerical simulations in a simplified inflow-outflow premixed configuration. The thermochemical conditions are chosen to match those of the most reactive mixture in the Engine Combustion Network’s n-dodecane Spray A flame. Similar to previous work (Savard et al., Combust. Flame 208 (2019) 402–419) a transition of the stabilization mode from spontaneous ignition to deflagration is observed upon decreasing inflow velocity and/or increasing turbulent Reynolds number. However, for the present conditions there is a regime over which cool flames transition to deflagrations, while hot flames remain stabilized by spontaneous ignition, being pushed further away from the inlet. As cool flames transition to deflagrations, HTC ignition delay is increased considerably (up to 2.5 times larger). In addition, the flame structure in phase space is found to be strongly affected by the transition to deflagration, especially in cool flames. The mechanism controlling the transition, characterized by a reduction in displacement speed, differs between hot and cool flames: the former is attributed to an increase in progress variable gradients while the latter is attributed to a reduction in chemical source terms. The above trends are shown to correlate very well with a transition function and a similar functional dependence is found in laminar flames. Finally, a chemical explosive mode analysis provides further insight into the observed phenomena.