Kinetic Energy Balance Research Articles

Morphology and dynamics of the liquid jet in high-speed gas-assisted atomization retrieved through synchrotron-based high-speed X-ray imaging

The breakup of a liquid jet by a surrounding high-speed gas jet with different liquid Reynolds numbers and gas Weber numbers was studied using high speed phase-contrast X-ray imaging technique. Focusing on the liquid core, the portion of liquid that is connected to the nozzle, four distinct morphologies were observed and can be associated with changes in the large-scale configurations of the two-phase flow are reported in a phase diagram. Gas-to-liquid kinetic energy balance arguments capture several transitions between the liquid core regimes. The temporal evolution of the center of mass of the liquid core is extracted to quantify its motion, whose statistics can be utilized as a signature to distinguish different regimes. At low to moderate gas Weber numbers, the dynamics are strongly influenced by flapping, while long-time dynamics develop at high Weber numbers, that give way to quasi-periodic motions when swirl is impeded to the gas jet.

On the Tropical Cyclone Integrated Kinetic Energy Balance

AbstractCurrent global historical reanalyzes prevent to adequately examine the role of the near‐core surface wind structural properties on tropical cyclones climate trends. Here we provide theoretical and observational evidences that they are crucial for the monitoring of integrated kinetic energy. The kinetic energy balance is reduced to a simple rule involving two parameters characterizing the surface wind structure and directly suggested by the governing equations. The theory is uniquely verified with a database of high‐resolution ocean surface winds estimated from all‐weather spaceborne synthetic aperture radar. Such measurements provide indirect estimates of a multiplicative constant modulating the kinetic energy balance and associated with the system thermodynamics. Consequently, accumulated high‐resolution acquisitions of the ocean surface shall allow to better monitor the integrated kinetic energy and provide new means to tackle climatological studies of tropical cyclones destructiveness.

Pressure-Driven Switching of Photoelectron Impact Ionization-Chemical Ionization/Penning Ionization in Vacuum Ultraviolet Photoionization Mass Spectrometry.

Vacuum ultraviolet photoionization (VUV-PI) is a soft ionization technique that operates under pressures ranging from vacuum to ambient pressure. VUV-PI has played an essential role in direct sampling mass spectrometry. In this study, new ionization processes initiated by photoelectrons have been studied through the inclusion of a radio frequency (RF) electric field at different pressures. After deducting the contribution of single photoionization (SPI), the signal intensity of 1 ppmv toluene (C7H8+) in Ar was approximately 5-fold higher than that in N2. Mixed gases with different ionization energies (IEs) and excitation energies (EEs) were further investigated to reveal that metastable species were involved in the enhancement process. Reactant ions were produced by photoelectron impact ionization (PEI), which further triggered ion-molecule reactions, i.e., chemical ionization (CI). Metastable species were produced by photoelectron impact excitation (PEE), which further triggered Penning ionization (PenI). Analytes with IEs above 10.6 eV, such as CO2 (IE = 13.78 eV) and CHCl3 (IE = 11.37 eV), could be sensitively ionized by PenI with a sensitivity comparable to SPI. Except for the contribution of SPI, the dominant ionization process was switched from PEI-CI to PenI when the pressure was elevated from 50 to 500 Pa, as the electron energy gradually decreased and was only able to produce metastable states based on the kinetic energy balance equation of electrons. The conversion processes and conditions from PEI-CI to PenI will provide novel insights to develop new selective and sensitive VUV-PI sources and understand the ionization mechanism in other discharge ionization sources.

An interface tracking, finite volume code for modeling axisymmetric implosion of a rotating liquid metal liner with free surface

We present Integrated System Model-hydrodynamics (ISM-hydro)—an interface tracking, finite volume code for modeling a shaped implosion of a rotating, initially cylindrical, fluid shell (liner) with a free surface. The code is a novel implementation of the mixed Lagrangian–Eulerian approach, applied to a compressible fluid in an axisymmetric geometry described by cylindrical coordinates (r, ϕ, z). In ISM-hydro, a structured quadrilateral mesh follows fluid elements in the r-direction (radially Lagrangian) and is fixed in the z-direction (axially Eulerian). This approach accurately captures the motion of the liner's free surface, making it an interface tracking method. Using this mesh, we derive a finite volume discretization of the axisymmetric Euler equations for a rotating compressible fluid that has an exact balance of kinetic energy. An extensive comparison between ISM-hydro and the open-source software OpenFOAM is presented; results for different test cases show very good agreement in simulated implosion trajectories and flow fields. ISM-hydro is the purely hydrodynamic component of the Integrated System Model (ISM), a framework developed at General Fusion (GF) for comprehensive predictive modeling of GF's magnetized target fusion (MTF) scheme, where an imploding rotating liquid metal liner compresses a magnetized plasma target to fusion conditions. Among advantages of the code is its speed: a full implosion simulation with a coarse mesh takes on the order of one minute on a single core while preserving high accuracy. This makes ISM-hydro a valuable tool for the design optimization of GF's MTF machines.

Stability analysis of Poiseuille flow in an annulus partially filled with porous medium

The linear stability analysis of fluid flow, driven by an axial pressure gradient, inside the annular region partially filled with porous medium is investigated. The porous layer is attached to the inner cylinder. The flow is governed by the unsteady Darcy model in the porous region and the Navier–Stokes equation in the viscous region. The effect of the curvature parameter C (ratio of the inner cylinder radius to the gap between cylinders), the ratio of the fluid to the porous layer thickness (t̂), and the Darcy number (Da) on the stability characteristics are explored. In addition, the help of the radial velocity contours and the kinetic energy balance is taken to get an insight into the mode and the cause of instability, respectively. The results show that depending upon the value of t̂, a decrease in the value of C causes a shift in the neutral stability curve from bimodal to trimodal. For low values of t̂, when the onset of instability is dominated by a porous mode, C destabilizes the flow, whereas it has a stabilizing impact on the flow stability for the odd-fluid mode and the even-fluid mode. At high values of t̂, C has again destabilizing characteristics and instability is dominated by even-fluid mode. When axisymmetric disturbances are dominant, it is observed that the value of t̂ for which similar instability characteristics are found varies directly as the square root of Da. However, the correlation between t̂ and Da does not hold when the non-axisymmetric disturbances are least stable. Contrary to the unconditional stability of the annular Poiseuille flow under non-axisymmetric disturbances for C < 0.1325, the present system is unstable even for C = 0.005 and t̂≤1. This shows the significant impact of the curved fluid–porous interface on the stability characteristics.

Weakly nonlinear stability analysis of non-isothermal parallel flow in a vertical porous annulus

The study examines the stability of parallel airflow within a tall vertical coaxial circular annulus filled with a highly permeable porous medium under stable stratification. The linear stability theory predicts that the least unstable mode can be either axisymmetric or non-axisymmetric, depending on the values of the governing parameters. The curvature parameter, defined as the gap between coaxial circular cylinders, contributes to the stabilization of the flow. Depending on various controlling parameter values, the stably stratified non-isothermal annular parallel flow (SNAPF) can manifest three instability modes: thermal-shear, thermal-buoyant, and mixed or interactive. The instability type can change abruptly with Reynolds number, curvature parameter, and media permeability. A finite-amplitude instability analysis is examined using weakly nonlinear stability theory. The analysis demonstrates both subcritical and supercritical bifurcations near the instability boundary. The range of Reynolds numbers for subcritical bifurcation expands when switching from axisymmetric to non-axisymmetric disturbance. Bifurcation transitions between supercritical and subcritical occur due to changes in the least stable azimuthal mode. The study also investigates the equilibrium/threshold amplitude within the supercritical/subcritical instability regime, and it verifies the existence of subcritical/supercritical bifurcation through nonlinear kinetic energy balance. Furthermore, the finite-amplitude analysis anticipates that the lower critical Rayleigh number increases as the Reynolds number, curvature parameter, or media permeability decreases. An increase in the Reynolds number shifts the point of inflection in the velocity profile toward the inner cylinder, which subsequently leads to a reduction in the size of the core vortex region. In the subcritical instability regime, the radius of the primary vortex cell decreased significantly as the Rayleigh number increased. When the curvature is altered, a structural transition occurs in the isotherms from multicellular to unicellular.

Assessment of Turbulent Kinetic Energy Balance within the Boulder Array in Gravel Bed Stream

Assessment of Turbulent Kinetic Energy Balance within the Boulder Array in Gravel Bed Stream

Reynolds number dependence of turbulent kinetic energy and energy balance of 3-component turbulence intensity in a pipe flow

Measurement data sets are presented for the turbulence intensity profile of three velocity components ( $u$ , $v$ and $w$ ) and turbulent kinetic energy (TKE, $k$ ) over a wide range of Reynolds numbers from $Re_\tau =990$ to 20 750 in a pipe flow. The turbulence intensity profiles of the $u$ - and $w$ -component show logarithmic behaviour, and that of the $v$ -component shows a constant region at high Reynolds numbers, $Re_\tau >10\,000$ . Furthermore, a logarithmic region is also observed in the TKE profile at $y/R=0.055\unicode{x2013}0.25$ . The Reynolds number dependences of peak values of $u$ -, $w$ -component and TKE fit to both a logarithmic law (Marusic et al., Phys. Rev. Fluids, vol. 2, 2017, 100502) and an asymptotic law (Chen and Sreenivasan, J. Fluid Mech., vol. 908, 2020, R3), within the uncertainty of measurement. The Reynolds number dependence of the bulk TKE $k^+_{bulk}$ , which is the total amount of TKE in the cross-sectional area of the pipe also fits to both laws. When the asymptotic law is applied to the $k^+_{bulk}$ , it asymptotically increases to the finite value $k^+_{bulk}=11$ as the Reynolds number increases. The contribution ratio $\langle u'^2\rangle /k$ reaches a plateau, and the value tends to be constant within $100< y^+<1000$ at $Re_\tau >10\ 000$ . Therefore, the local balance of each velocity component also indicates asymptotic behaviour. The contribution ratios are balanced in this region at high Reynolds numbers as $\langle u'^2\rangle /k\simeq 1.25$ , $\langle w'^2\rangle /k\simeq 0.5$ and $\langle v'^2\rangle /k \simeq 0.25$ .

Characterization of energy transfer and triadic interactions of coherent structures in turbulent wakes

Turbulent wakes are often characterized by dominant coherent structures over disparate scales. Dynamics of their behaviour can be attributed to interscale energy dynamics and triadic interactions. We develop a methodology to quantify the dynamics of kinetic energy of specific scales. Coherent motions are characterized by the triple decomposition and used to define mean, coherent and random velocity. Specific scales of coherent structures are identified through dynamic mode decomposition, whereby the total coherent velocity is separated into a set of velocities classified by frequency. The coherent kinetic energy of a specific scale is defined by a frequency triad of scale-specific velocities. Equations for the balance of scale-specific coherent kinetic energy are derived to interpret interscale dynamics. The methodology is demonstrated on three wake flows: (i) ${Re}=175$ flow over a cylinder; (ii) a direct numerical simulation of ${Re}=3900$ flow over a cylinder; and (iii) a large-eddy simulation of a utility-scale wind turbine. The cylinder wake cases show that energy transfer starts with vortex shedding and redistributes energy through resonance of higher harmonics. The scale-specific coherent kinetic energy balance quantifies the distribution of transport and transfer among coherent, mean and random scales. The coherent kinetic energy in the rotor scales and the hub vortex scale in the wind turbine interact to produce new scales. The analysis reveals that vortices at the blade root interact with the hub vortex formed behind the nacelle, which has implications for the proliferation of scales in the downwind near wake.

An energetic signature for breaking inception in surface gravity waves

A dynamical understanding of the physical process of surface gravity wave breaking remains an unresolved problem in fluid dynamics. Conceptually, breaking can be described by inception and onset, where breaking inception is the initiation of unknown irreversible processes within a wave crest that precede the visible manifestation of breaking onset. In the search for an energetic indicator of breaking inception, we use an ensemble of non-breaking and breaking crests evolving within unsteady wave packets simulated in a numerical wave tank to investigate the evolution of each term in the kinetic energy balance equation. We observe that breaking onset is preceded by around one quarter of a wave period by a rapid increase in the rate of convergence of kinetic energy that triggers an irreversible acceleration of the kinetic energy growth rate. This energetic signature, which is present only for crests that subsequently break, arises when the kinetic energy growth rate exceeds a critical threshold. At this point the additional kinetic energy convergence cannot be offset by converting excess kinetic energy to potential energy or by dissipation through friction. Our results suggest that the ratio of the leading terms of the kinetic energy balance equation at the time of this energetic signature is proportional to the strength of the breaking crest. Hence this energetic inception point both predicts the occurrence of breaking onset and indicates the strength of the breaking event.

Impact of dobutamine stress on diastolic energetic efficiency of healthy left ventricle: an in vivo kinetic energy analysis.

The total kinetic energy (KE) of blood can be decomposed into mean KE (MKE) and turbulent KE (TKE), which are associated with the phase-averaged fluid velocity field and the instantaneous velocity fluctuations, respectively. The aim of this study was to explore the effects of pharmacologically induced stress on MKE and TKE in the left ventricle (LV) in a cohort of healthy volunteers. 4D Flow MRI data were acquired in eleven subjects at rest and after dobutamine infusion, at a heart rate that was ∼60% higher than the one in rest conditions. MKE and TKE were computed as volume integrals over the whole LV and as data mapped to functional LV flow components, i.e., direct flow, retained inflow, delayed ejection flow and residual volume. Diastolic MKE and TKE increased under stress, in particular at peak early filling and peak atrial contraction. Augmented LV inotropy and cardiac frequency also caused an increase in direct flow and retained inflow MKE and TKE. However, the TKE/KE ratio remained comparable between rest and stress conditions, suggesting that LV intracavitary fluid dynamics can adapt to stress conditions without altering the TKE to KE balance of the normal left ventricle at rest.

An EMA-conserving, pressure-robust and Re-semi-robust method with A robust reconstruction method for Navier–Stokes

Proper EMA-balance (balance of kinetic energy, linear momentum and angular momentum), pressure-robustness and Re-semi-robustness (Re: Reynolds number) are three important properties of Navier–Stokes simulations with exactly divergence-free elements. This EMA-balance makes a method conserve kinetic energy, linear momentum and angular momentum in an appropriate sense; pressure-robustness means that the velocity errors are independent of the pressure; Re-semi-robustness means that the constants appearing in the error bounds of kinetic and dissipation energies do not explicitly depend on inverse powers of the viscosity. In this paper, based on the pressure-robust reconstruction framework and certain suggested reconstruction operators in Linke and Merdon [Comput. Methods Appl. Mech. Eng. 311 (2016) 304–326], we propose a reconstruction method for a class of non-divergence-free simplicial elements which admits almost all the above properties. The only exception is the energy balance, where kinetic energy should be replaced by a suitably redefined discrete energy. The lowest order case is the Bernardi–Raugel element on general shape-regular meshes. Some numerical comparisons with exactly divergence-free methods, the original pressure-robust reconstruction methods and the EMAC method are provided to confirm our theoretical results.

Explaining Dynamics and Rapid Onset of the Somali Jet through Its Kinetic Energy Budget

Abstract The low-level Somali jet is the primary mechanism of moisture transport for the South Asian monsoon. It precedes monsoon onset over India and shares its key characteristic features such as rapid intensification and slower retreat during seasonal evolution. This study analyzes the kinetic energy (KE) budget of Somali jet region using high-spatiotemporal-resolution reanalysis (ERA5) to explain these key features. The KE budget reveals that in the Southern Hemisphere, the easterly flow that ultimately feeds the jet exhibits a conventional Ekman balance, with KE generation balanced by frictional dissipation. A unique “advective balance”—balance between KE generation in the northward flow and its advection emerges as the jet begins to form near the equatorial region. The fully formed Somali jet exhibits a three-way balance between KE generation, its advection, and dissipation. A nondimensional parameter–boundary layer local Rossby number (Ro) characterizes the transitions across these regimes. The large-Ro regime describes an advective balance under which KE-generating meridional winds become proportional to meridional pressure gradients yielding a nonlinear (quadratic) dependence of KE generation on pressure gradients. This nonlinear relation explains rapid onset of the jet as well as the asymmetry between rapid onset and slower retreat, leading us to propose a simple model for approximating the seasonal evolution of kinetic energy in the Somali jet given the evolution of pressure gradients. In summary, this work shows that Somali jet onset is closely tied to the seasonal evolution of Ro in the region where the advective boundary layer appears. Significance Statement The Somali jet is an important feature of the South Asian monsoon, contributing significantly to enhanced rainfall over the region. We study the dynamics of this jet by focusing on its kinetic energy (KE). Maintenance of the jet at different regions corresponds to different kinds of balances in the kinetic energy budget. A dimensionless parameter characterizes these different regimes of KE balance, which are captured at sufficiently high resolution. The rapid intensification of the jet can be explained as a nonlinear response of KE generation to the seasonal evolution of the north–south pressure gradient. These findings contribute to understanding of the jet and its nonlinear evolution, which is important for accurate representation and simulation of the Somali jet in climate models.

Magnetohydrodynamic mixed convection flow of liquid metals in a vertical channel: A stability analysis

The impact of applied magnetic field on liquid metal flows has good prospects for the industry. For a better understanding of flow dynamics, the stability analysis of liquid metal flows through a confined transverse magnetic field is of fundamental importance in designing advanced magnetohydrodynamic (MHD) devices for the next generation. In this paper, we report the linear stability analysis of mixed convection flow of electrically conducting liquid metals with low Prandtl number (Pr) in a vertical channel under a transverse magnetic field. The flow is described by quasi-static MHD approximation. The instability properties are examined numerically through a spectral collocation method. The influence of magnetic field on instability mechanism is examined for a good range of Pr. The results demonstrate that the growth of the infinitesimal disturbance decreases with increasing strength of the applied magnetic field due to the effective Lorentz force exerted on the flow, i.e., stability of the flow increases. In contrast, the stability of the basic flow decreases on increasing the value of Pr, except for a small range of Pr, where it increases. The kinetic energy balance shows that for very small values of Pr, the shear instability dominates the flow, whereas for relatively larger values of Pr, thermal-buoyant instability plays a significant role in the instability mechanism. The dissipation of energy in the kinetic energy balance occurs prominently due to the presence of the applied magnetic field. The secondary flow pattern shows that the applied magnetic field suppresses the disturbance in the vicinity of channel walls. In contrast, a decrease in thermal diffusivity provokes instability by inviting a strong disturbance cell in the middle portion of the channel. The energy dissipation in the kinetic energy balance occurs mainly due to the presence of the magnetic field.

Kinetic Energy Generation in Cross‐Equatorial Flow and the Somali Jet

AbstractIn response to north‐south pressure gradients set by the annual march of the Sun, a cross‐equatorial flow that turns to become a low‐level Somali Jet at around 10°N is established in the lower troposphere over the Indian Ocean. This flow plays a fundamental role in the Indian monsoon. A mechanistic understanding of drivers of this flow is lacking. Here, we present a seasonal‐mean analysis of the kinetic energy (KE) budget of the low‐level flow using high spatiotemporal resolution ERA5 reanalysis to identify sources and sinks of KE. We find that the largest KE generation occurs around East African orography where the Somali Jet forms while significant KE is also generated over the Western Ghats and the Madagascar Island (“hot spots”). These regions are distant from core monsoon precipitation regions, suggesting that local circulations driven by condensation do not directly produce the bulk of KE during monsoons. A unique KE balance supports the generation of the Somali Jet, with KE generation balanced by nonlinear KE advection as it forms. Over oceans, KE generation occurs mainly due to cross‐isobaric meridional winds in the boundary layer (BL). In contrast, over the East African highlands and Western Ghats, KE generation maximizes just above the BL and mainly occurs due to the interaction of flow with orography. We propose a simple decomposition of lower tropospheric KE generation into contributions from surface pressure, orography, and free‐tropospheric gradients that corroborate the important role played by surface pressure gradients once adjusted for effects of orography.

HHO Methods for the Incompressible Navier-Stokes and the Incompressible Euler Equations

We propose two Hybrid High-Order (HHO) methods for the incompressible Navier-Stokes equations and investigate their robustness with respect to the Reynolds number. While both methods rely on a HHO formulation of the viscous term, the pressure-velocity coupling is fundamentally different, up to the point that the two approaches can be considered antithetical. The first method is kinetic energy preserving, meaning that the skew-symmetric discretization of the convective term is guaranteed not to alter the kinetic energy balance. The approximated velocity fields exactly satisfy the divergence free constraint and continuity of the normal component of the velocity is weakly enforced on the mesh skeleton, leading to H-div conformity. The second scheme relies on Godunov fluxes for pressure-velocity coupling: a Harten, Lax and van Leer approximated Riemann Solver designed for cell centered formulations is adapted to hybrid face centered formulations. The resulting numerical scheme is robust up to the inviscid limit, meaning that it can be applied for seeking approximate solutions of the incompressible Euler equations. The schemes are numerically validated performing steady and unsteady two dimensional test cases and evaluating the convergence rates on h-refined mesh sequences. In addition to standard benchmark flow problems, specifically conceived test cases are conducted for studying the error behaviour when approaching the inviscid limit.

On the use of kinetic energy balance for the volumetric identification of drag sources of a blunt body. Application to road vehicles

A volumetric identification of drag sources is proposed using the Reynolds equation for the integral mean momentum and mean flow kinetic energy balance. This methodology works independently of the turbulence model used in CFD and relies on a physical interpretation. The approach, developed in the context of automotive engineering, is of general use. A road vehicle is indeed a complex multi-scale geometry and all the flow regions are interacting. As far as the kinetic energy of the mean flow is concerned, the main volumetric loss is production of turbulent kinetic energy at all relevant sub-scales of the body. The quantitative link to the power of the mean drag force is derived from first principles. For practical applications, the volume integral used to compute the volumetric losses can be decomposed in user-defined regions and integrated into optimization loops. Indeed, if losses in a given flow region are minimized, consequences can be precisely and quantitatively evidenced for all other regions. Applications to a model two-dimensional test case and a real car geometry are discussed.

Linear stability perspective on mixed convection flow of nanofluids in a differentially heated vertical channel

We report instability properties of mixed convection flow of different nanofluids in a differentially heated vertical channel through a linear stability analysis. A single-phase nanofluid model is used to report the instability mechanism of nanofluids, which fairly works for the low concentration of the nanoparticles. The stability results are examined for five different types of water-based nanofluids. The basic flow and linear disturbance equations are solved with the Chebyshev spectral collocation method. The influence of nanoparticles volume fraction (φ) in different water-based nanofluids is analyzed in terms of growth rate analysis, instability boundaries and kinetic energy analysis. The results reveal that increasing the concentration of nanoparticles in the water improves the stability of the basic flow. However, increasing the Reynolds number (Re) value destabilizes the basic flow of nanofluid due to the dominant nature of the shear force. Compared to conventional pure water fluid, the inclusion of nanoparticles in pure water delays the onset of instabilities by reducing the growth of the disturbance. The order of stability for different nanofluids in (φ,Gr/Re)-plane is observed as: Al2O3/water >TiO2/water >CuO/water >Cu/water >Ag/water nanofluid, where Gr is Grashof number. By increasing the volume percentage of nanoparticles, the friction coefficient at the heated wall of the channel decreases. The kinetic energy balance at the critical level shows that shear instability is the most dominant instability for considered nanofluids.

Jet impingement on the underside of a superhydrophobic surface

Water patch topology and momentum loss resulting from a jet impacting on the underside of a flat plate with varied hydrophobicity were studied. The jet's Reynolds and Froude numbers ranged from 3700 to 31 000, and from 1 to 23, respectively. Hence effects of gravity were expected to be non-negligible, and data suggest that this is the case for hydrophobic surfaces. The interplay of gravity, surface tension, inertia and viscosity resulted in two distinct behaviours. On hydrophilic surfaces, water spread uniformly. Friction reduced momentum, and led to accumulation at the edges of the patch until gravity overcame surface tension and produced droplets. On hydrophobic surfaces, two rims formed, enclosing a thin laminar film. The patch shape was mostly determined by the balance of kinetic and surface energy. Dewetting occurred in most cases when the two rims merged, but for a narrow parameter, range water detached soon after impact and formed a type of skewed water bell. The transition in detachment topology was predicted reasonably by a simple model considering whether an attached or detached rim minimizes energy. Due to promotion of dewetting by gravity, the water patch area decreased compared to that reported in previous studies, which considered jet impingement on vertical surfaces and tops of horizontal surfaces. Owing to the application that motivated this study, the streamwise force on the plate was also measured. On hydrophobic surfaces the reduction in force correlated with the reduction in water patch area. Water patch area and momentum loss were both found to scale best with the contact-angle-modified Weber number.

Mean and Turbulent Characteristics of a Bottom Mixing‐Layer Forced by a Strong Surface Tide and Large Amplitude Internal Waves

AbstractWe present 15 days of both mean and turbulent field observations bottom mixing‐layer at a gently sloping 250 m deep continental shelf site, energized by tides and nonlinear internal waves (NLIWs). The tidal frequency forcing was due to the combined effects of the barotropic tide and a mode‐1 internal tide (IT), while the NLIWs were predominantly mode‐1 waves of depression. The bottom mixing‐layer thickness varied at both semidiurnal and sub‐tidal ∼O(10)d frequencies, with an average thickness of around 10 m. Compression and expansion of the mixing‐layer by both the IT and NLIWs affected the mean velocity profiles in the mixing‐layer, while the phasing between the barotropic and baroclinic flows led to an asymmetry in mean velocity profiles between periods of rising and falling isotherms. With the exception of periods of flow reversal, the turbulent kinetic energy balance and turbulent stress observations were consistent with the existence of an inertial‐sublayer with thickness of approximately 10%–15% of the mixing‐layer thickness ( ∼1 m), even beneath NLIWs. In the outer portion of the mixing‐layer—that is, above the inertial‐sublayer—NLIWs modulated the local turbulence spectra. We discuss the observations in the context of a predictive model for mixing‐layer thickness. The analysis suggests that the high‐frequency variability in mixing‐layer thickness was dominated by internal wave pumping, though strength of the ambient stratification and the frequency of the forcing were important controls on the time‐averaged (sub‐tidal) variation.