Concentrated Vortex Research Articles

The Impact of Outer-Core Surface Heat Fluxes on the Convective Activities and Rapid Intensification of Tropical Cyclones

AbstractThe rapid intensification (RI) of Typhoon Soudelor (2015) is simulated using a full-physics model. To investigate how the outer-core surface heat fluxes affect tropical cyclone (TC) structure and RI processes, a series of numerical experiments are performed by suppressing surface heat fluxes between various radii. It is found that a TC would become quite weaker when the surface heat fluxes are suppressed outside the radius of 60 or 90 km [the radius of maximum surface wind in the control experiment (CTRL) at the onset of RI is roughly 60 km]. However, interestingly, the TC would experience stronger RI when the surface heat fluxes are suppressed outside the radius of 150 km. For those sensitivity experiments with capped surface heat fluxes, the members with greater intensification rate show stronger inner-core mid- to upper-level updrafts and higher heating efficiency prior to the RI periods. Although the outer-core surface heat fluxes in these members are suppressed, the inner-core winds become stronger, extracting more ocean energy from the inner core. Greater outer-core low-level stability in these members results in aggregation of deep convection and subsequent generation and concentration of potential vorticity inside the inner core, thus confining the strongest winds therein. The abovementioned findings are also supported by partial-correlation analyses, which reveal the positive correlation between the inner-core convection and subsequent 6-h intensity change, and the competition between the inner-core and outer-core convections (i.e., eyewall and outer rainbands).

Investigation of crossflow features of a slender delta wing

In the present work, the main features of primary vortices and the vorticity concentrations downstream of vortex bursting in crossflow plane of a delta wing with a sweep angle of Λ=70° were investigated under the variation of the sideslip angles, Β. For the pre-review of flow structures, dye visualization was conducted. In connection with a qualitative observation, a quantitative flow analysis was performed by employing Particle Image Velocimetry (PIV). The sideslip angles, Β were varied with four different angles, such as 0°, 4°, 12°, and 20° while angles of attack, α were altered between 25° and 35°. This study mainly focused on the instantaneous flow features sequentially located at different crossflow planes such as x/C=0.6, 0.8 and 1.0. As a summary, time-averaged and instantaneous non-uniformity of turbulent flow structures are altered considerably resulting in non-homogeneous delta wing surface loading as a function of the sideslip angle. The vortex bursting location on the windward side of the delta wing advances towards the leading-edge point of the delta wing. The trajectory of the primary vortex on the leeward side slides towards sideways along the span of the delta wing. Besides, the uniformity of the lift coefficient, CL over the delta wing plane was severely affected due to unbalanced distribution of buffet loading over the same plane caused by the variation of the sideslip angle, Β. Consequently, dissimilarities of the leading-edge vortices result in deterioration of the mean value of the lift coefficient, CL.

Structure and dynamics of concentrated mesoscale vortices in planetary atmospheres

Concentrated vortices are spatially localized structures with nonzero vorticity surrounded by a potential flow. These structures include a broad class of mesoscale vortices, such as dust devils, water vortices, and fire vortices, as well as larger-scale and more intense tornados. From a rather broad class of concentrated mesoscale vortices, dust devils are selected as the simplest and most easily observable structures owing to dust particles that play the role of tracers. The aim of this review is to present the main results of studies of dust devils in the atmospheres of Earth and Mars. In the framework of ideal fluid dynamics, a recently proposed model is discussed that allows describing vortex structures that are fully localized in space. The results of numerical modeling of vortex dynamics and an analytic model of vortex generation in a convectively unstable atmosphere are briefly discussed.

Wave interactions in neutrally stable shear layers: Regular and singular modes, and non-modal growth

A recent letter [J. R. Carpenter and A. Guha, “Instability of a smooth shear layer through wave interactions,” Phys. Fluids 31, 081701 (2019)] compared the neutral modes of a smooth two-dimensional shear profile without an inflection point to the modes of its corresponding piecewise-linear profile. The regular mode in the smooth profile was identified as the one least sensitive to the numerical resolution, while the singular modes displayed high sensitivity. Here, we provide a physical interpretation using a wave interaction approach for understanding the structure and behavior of both the regular and singular modes. The regular modes are the interfacial Rossby waves located at the concentrated mean vorticity gradient of the shear profile. In contrast, the singular modes result from a one way phase-locking interaction between singular vorticity disturbances, passively advected by the mean flow at different levels of the profile, and the interfacial Rossby waves. We show that this one way interaction can also lead to a sustained non-modal growth of the interfacial Rossby waves that cannot be captured by standard eigenvalue analysis.

The Preliminary Exploration of Micro-Friction Stir Welding Process and Material Flow of Copper and Brass Ultra-Thin Sheets.

In the friction stir welding (FSW) of ultra-thin dissimilar metal sheets, different physical material properties, the reduction of plastic metal in the weld zone, and insufficient plastic metal flow lead to poor weld seam shapes and joint qualities. Therefore, it is necessary to study the flow behavior during the FSW of ultrathin sheets. In this study, micro friction stir welding (μFSW) was conducted and analyzed for the butt welding of 0.6-mm-thick ultrathin brass (H62-H) and pure copper (T2-Y) sheets. By analyzing the electric signals of the temperature and force during the welding process, testing the mechanical properties, and analyzing the metallography of the joint, the influences of the process parameters on the metal flow behavior during μFSW were studied. In the proper process conditions, the material preferentially migrated and concentric vortex flow occurred in the vicinity of the shoulder and tool pin action areas. The copper was pushed from the retreating side (RS) to the advancing side (AS) of the weld, allowing it to flow more fully. A mixture of both materials formed at the bottom of the weld nugget, and less migration occurred in the heat-affected zone of the AS at this time. The highest tensile strength can reach 194 MPa, accounting for 82.6% of the copper. The presence of brittle phases Cu5Zn8, AgZn3 and AgZn caused the hardness to fluctuate slightly.

Impingement of a counter-rotating vortex pair on a wavy wall

In this paper, we investigate the impingement of a two-dimensional (2-D) vortex pair translating downwards onto a horizontal wall with a wavy surface. A principal purpose is to compare the vortex dynamics with the complementary case of a wavy vortex pair (deformed by the long-wavelength Crow instability) impinging onto a flat surface. The simpler case of a 2-D vortex pair descending onto a flat horizontal ground plane leads to the well known ‘rebound’ effect, wherein the primary vortex pair approaches the wall but subsequently advects vertically upwards, due to the induced velocity of secondary vorticity. In contrast, a wavy vortex pair descending onto a flat plane leads to ‘rebounding’ vorticity in the form of vortex rings. A descending 2-D vortex pair, impinging on a wavy wall, also generates ‘rebounding’ vortex rings. In this case, we observe that the vortex pair interacts first with the ‘hills’ of the wavy wall before the ‘valleys’. The resulting secondary vorticity rolls up into a concentrated vortex tube, ultimately forming a vortex loop along each valley. Each vortex loop pinches off to form a vortex ring, which advects upwards. Surprisingly, these rebounding vortex rings evolve without the strong axial flows fundamental to the wavy vortex case. The present research is relevant to wing tip trailing vortices interacting with a non-uniform ground plane. A non-flat wall is shown to accelerate the decay of the primary vortex pair. Such a passive, ground-based method to diminish the wake vortex hazard close to the ground is consistent with Stephan et al. (J. Aircraft, vol. 50 (4), 2013a, pp. 1250–1260; CEAS Aeronaut. J., vol. 5 (2), 2013b, pp. 109–125).

Numerical Characterization of Natural Swirling Flame Evolving in Free Environment via FDS: a Comprehensive Investigation of Fires Problems

In this paper, a numerical study of a swirling flame generated through the interaction between a central fire and its surrounding fires is performed. A swirling flame can be configured by installing a secondary’s sources surrounding the central source, organized in an asymmetrical manner in order to ensure circumferential entrainment of the central flame by the supply puffs air. An analysis is performed to study this kind of flow. This analysis highlights the different zones that characterize the vertical propagation of a swirling flame; a first zone, close to the fire source, characterized by an acceleration of the flow and an increase of the temperature. A second zone marked by the passage of the temperature by a maximum while changing variation with a net decrease of the flow acceleration and a third zone where the thermal and dynamic fields change and gradually decrease. Moreover, this study shows an axisymmetric flow behavior with two different aspects of its global structure. A central region characterized by a block motion (solid core) where the flow is rotational, characterized by a concentration of vorticity, and surrounded by the rest of the space where the flow is irrotational. Moving vertically away from the active source, results show an attenuation of the axial vortex intensity which is accompanied by a disappearance of movement by block. The centerline evolution of the axial and azimuthal momentum flux enables also to highlight these different aspects of the global flow structure.

Genesis of Antibiotic Resistance LIII: “Virchow’s Triad” of Capillary (Vascular) Leak Syndrome (CLS) tethered Adverse Pressure Gradient exacerbated mortality rate in NCT01663701: A critical appraisal

Based on adverse effects of biosimilar(s), for oncological treatment modalities (radiation/chemotherapy), posted in FAERS and VigiBase, an effort has been made to derive a temporal correlation between CLS and hemodynamic (Fluid dynamic/mechanics properties) dysregulation lead exacerbated mortality rate in NCT01663701. Idiopathic (unknown etiology) systemic capillary leak syndrome (SCLS) or Capillary leak syndrome (CLS), also known as vascular leak syndrome (VLS), with clinical features such as leakage of the plasma (reversible plasma extravasation with fluid resuscitation), vascular collapse accompanied by a classic triad of hypoalbuminemia, hemoconcentration, and hypotension in the absence of secondary causes of shock with edema. Fluid management is an effective clinical management strategy for an improved prognosis (verbatim in part and modified from J Clin Med. 2018; seven (11); J Clin Med. 2019; 8(2)). The clinical presentation of CLS with a corollary of Virchow’s triad ( https://www.ncbi.nlm.nih.gov/books/NBK539697/) and the critical events for a laminar to turbulence transition ( ELTT) is systematically correlated. Virchow’s triad I ‐ Endothelial damage:ELTT 1. Region of instability of small wavy disturbances called Tollmien‐Schlichting wave ELTT 2. Periodicity accompanied by the appearance of vortices ELTT 3. Peak‐Valley development in vortices, ELTT 4. Vorticity concentration and shear layer development with inflectional profile appearance and disappearance in Tollmien‐Schlichting wave pattern, Virchow’s triad II ‐ Venous stasis: ELTT 5. Breakdown: evolution of a staggered vortex pattern twice the wavelength of Tollmien‐Schlichting waves ( a high frequency fluctuations of hairpin eddies ‐ eddy currents, disrupts the laminar flow of blood, bringing platelets in close contact with the vascular wallVirchow’s triad III ‐ Hypercoagulability: ELTT 6. Cascading of vortices and turbulent‐spot development, (spots of thrombus lead to increased turbulence thus reduction in blood flow. Infarction and ischemia Thrombi often result in reduced blood flow to tissue (ischemia) or complete obstruction (absolute irreversible stasis NFP=0 mmHG, ?) of blood flow leading to cell death(infarction) with concurrent impairment of global net filtration pressure (NFP) in mark transition of laminar to turbulent flow pattern. Taken together, herewith it is suggested that a better understanding of the components of multifactorial mode of turbulence modelling in particular on time scale, blood viscosity, velocity profile, NFP gradient, and structural integrity of blood vessels (endothelial damage) of the capillary bed in the context of thromboembolic events [DDx: ischemic stroke(CVA), disseminated intravascular coagulation (DIC), deep vein thrombosis (DVT), pulmonary embolism and CLS], would enable better stratification of clinical risk factors, precision in clinical decision making amalgamating differential diagnosis for an accurate prognosis in early resuscitation protocol on sepsis such as NCT01663701.Support or Funding InformationSupported by professional development funds by SWTJC to Subburaj Kannan

Measurements of a Mach 3.4 turbulent boundary layer using stereoscopic particle image velocimetry

Experiments were performed within the Rutgers University Mach 3.4 supersonic wind tunnel to quantify the turbulent boundary layer in the test section, using stereoscopic particle image velocimetry (SPIV). Seeding of the tunnel was accomplished using atomized mineral oil, resulting in a Stokes number of 0.09. The Reynolds number based on momentum thickness and the friction-velocity Reynolds number were 64,000 and 4320, respectively, marking this as a high Reynolds number boundary layer. SPIV measurements were capable of resolving the mean velocity profile, along with turbulence quantities, permitting comparison against the known literature. Furthermore, the convection of vorticity concentrations representing hairpin vortices was observed within instantaneous vector fields. The resulting Reynolds stresses demonstrate that the boundary layer had typical values of anisotropy, while comparing well with data obtained within a slightly adverse pressure gradient. This was particularly noticeable from the trends in the Reynolds stresses, which exhibited higher-than-expected peak levels. These data provide a unique measurement of a supersonic turbulent boundary layer at Reynolds numbers not often encountered within existing data sets.

A point vortex transportation model for yawed wind turbine wakes

In this study, stereo particle imaging velocimetry measurements are performed at multiple streamwise locations behind a yawed wind turbine to reveal the formation mechanisms of the counter-rotating vortex pair (CVP), and a point vortex transportation (PVT) model is proposed to reproduce the top–down asymmetric kidney-shaped wake (also referred to as a curled wake). Results indicate that the CVP formed behind a yawed wind turbine originates from the complex interactions between the hub vortex and the streamwise components of the blade tip vortices, which is fundamentally different from the case of a yawed drag disk where the hub vortex is absent. Specifically, when the yaw angle exceeds a critical value, a small part of the streamwise vorticity shed from the rotor disk edge switches its sign from negative to positive and subsequently merges with the concentrated hub vortex under mutual induction, creating a patch of positive vorticity; meanwhile, the remaining streamwise vorticity distributed along the rotor edge curls and evolves into another patch of negative vorticity. These two patches of streamwise vorticity essentially constitute the CVP. Based on the physics learnt from the experiments, the non-uniform cross-stream velocity fields are first reconstructed by a cloud of point vortices distributed along the rotor edge and a hub vortex located in the rotor centre, and subsequently used to numerically solve a simplified transportation–diffusion equation of the wake velocity deficit, which altogether constitute the PVT model. This physics-based reduced-order model is the first model capable of accurately reproducing the wake deformation behind a yawed wind turbine.

Comparison of two interfacial flow solvers: Specific case of a single droplet impacting onto a deep pool

A numerical study about a droplet impacting onto a deep pool is presented here by employing the Volume of Fluid method to track the interface. In this investigation, two open source solvers, named Gerris and Basilisk, are used to solve the incompressible Navier–Stokes equations with free surface. The results are compared to provide some reference for the researchers involved in this research community. Firstly, the capabilities of the two solvers in simulating the droplet impacting problems are validated against available experimental results. And the adaptive mesh refinement techniques used in the two solvers are also found to be applicable. When simulating the drop impacting problems in an axisymmetric coordinate system, it is found that less meshes are produced in Gerris than that in Basilisk when similar adaptive criterion is adopted in both solvers. However, Basilisk still shows much higher computational efficiency due to its great superiority at parallelization, and thus less CPU time is required for such unsteady problems. When simulating moderate Reynolds number impacting problems, the two numerical solvers show perfect agreement (Re≤5000), however, since higher Reynolds numbers (Re≥5000) require smaller size of mesh in vicinity of the thin impacting region and the concentrated vortex region, it is hard for Gerris to obtain satisfactory results because of its poor computational efficiency. Thus, with such a high parallel capability and computational efficiency, Basilisk is introduced to solve a large number of cases. It is summarized that the flow pattern of the drop impacting problem can be classified to three categories. They are smooth ejecta sheet, main vortex shedding and Von Kármán vortex street. Each flow pattern relates to the vortex evolution inside the liquid closely. Basililsk also shows its potential in solving much more complicated three-dimensional problems. They cannot be completed by Gerris owing to its poor computational efficiency.

Drag reduction and flow structures of wing tip sails in ground effect

The hydrodynamics and flow structures of a base wing slotted with tip sails in proximity to the ground were studied experimentally in order to investigate the flow control efficiency of wing tip sails in ground effect. The experiment was conducted in a towing tank at a Reynolds number 1.5×105. The lift and drag forces were measured by a transducer, the velocity fields of the wing tip vortices were measured using a time-resolved particle image velocimetry system (TR-PIV). The tip-sails and ground clearance were both effective in reducing the total drag, the lift coefficients of the tip-sails wings were increased as compared with that of a base wing. The lift-drag ratios of the tip-sails wings were improved obviously in a range of angles of attack from 2° to stalling angle. The tip-sails played more important role in unwinding the concentrated wing tip vortices at higher angle of attack, the intensity of the tip vortices were much weaker than that of the base wing. The development of the wing tip vortices was suppressed as well due to the inhibition of the ground, the downwash speed was reduced and the induced drag was decreased.

Rotor boundary layer development in a two-stage compressor

This experimental study provides striking examples of the complex flow and turbulence structures resulting from blade–wake and wake–wake interactions in a multistage turbomachine. Particle image velocimetry measurements were performed within the second-stage rotors of a two-stage compressor. The first-stage stator wake is distorted and produces a kink structure in the second-stage rotor blades passage. This kink, also called a turbulent hot spot, with concentrated vorticity, high turbulence levels, and high turbulence kinetic energy, is caused by the interaction between the first-stage rotor wake and the stator wake. A high-speed region and a low-speed region are observed around the turbulent hot spot. The perturbation velocity is counterclockwise around the turbulent hot spot, with a magnitude much larger than that in the wake. The turbulent hot spot is more unstable and active than the wake and, thus, might play a pivotal role in the passage flow. The high turbulence and the negative jet behavior of the wake dominate the interaction between the unsteady wake and the separated boundary layer on the suction surface of the blade. When the upstream wake impinges on the blade, the boundary layer thickness first increases owing to the presence of the negative jet, and a thickened boundary layer region in the form of a turbulent spot is formed because of the high turbulence intensity in the wake. Then, the boundary layer gradually becomes thinner because of the presence of a calmed region that follows the thickened boundary layer region. Finally, the boundary layer gradually thickens again and recovers to separation. Thus, the boundary layer thickness is periodic in a wake passing cycle.

Calculation of gas flow rates in concentrated fire vortices

The article presents the results of numerical simulation of the generation of free fire vortices in the laboratory without the use of special twisting devices. A. Yu. Varaksin, the corresponding member of the Russian Academy of Sciences, in his experimental studies has described the principal possibility of physical modeling of the occurrence of concentrated fire vortices. In the model of a compressible continuous medium for the complete system of Navier — Stokes equations, an initial-boundary value problem has been proposed that describes complex three-dimensional unsteady flows of a viscous compressible heat-conducting gas in ascending swirling heat flows. We has constructed approximate solutions of the complete Navier — Stokes system of equations and has determined velocity characteristics of threedimensional unsteady gas flows initiated by local heating of the underlying surface by nineteen heat sources, using explicit difference schemes and the proposed initial-boundary conditions.

Heat transfer and flow characteristics in a sinusoidally curved converging-diverging channel

The objective of this work is to present the thermal performance characteristics and to examine the hydrodynamic structure of the fluid which improves the rate of heat transfer in parallel with the penalty of pressure drop by means of the time-averaged streamlines topology, <Ψ>, streamwise velocity distribution, <u>, vorticity concentration, <ω> and turbulent Reynolds stress, u'v'‾/U2 for the sinusoidal wavy channel. A wide range of experiments were performed for Reynolds numbers, Re ranging from 4 × 103 to 1 × 104 in order to determine the heat transfer rate and the friction factor, f with varying the channel height expansion/contraction ratio, M = Hmin/Hmax such as 0.5, 0.35 and 0.28. The results revealed that a significant heat transfer enhancement was achieved with a considerable penalty of pressure drop. The highest thermal performance factor, TPF was obtained as 1.46 for M = 0.5. Numerical simulations were conducted to confirm the experimental results for the same parameters. The Shear Stress Transport k-w (SST k-w) turbulence model was used to perform numerical analyses. After ensuring the consistency of experimental thermal performance results with numerical predictions, the Particle image velocimetry (PIV) system was utilized for investigating the flow physics in the sinusoidally curved converging-diverging channel for all M values at Re = 4 × 103 where the TPF is maximum.

Calculation of gas velocities in concentrated fire vortices

The article presents the results of numerical modeling of the generation of free fire vortices in laboratory conditions without the use of special swirling devices. The fundamental possibility of physical modeling of the occurrence of concentrated fire vortices is described in a series of experimental studies conducted under the supervision of A. Yu. Varaksin, corresponding member of the RAS. In the model of compressible continuous medium for the complete system of Navier-Stokes equations, an initial-boundary-value problem is proposed that describes complex three-dimensional unsteady flows of viscous compressible heat-conducting gas in ascending swirling heat flows. Using explicit difference schemes and the proposed initial-boundary conditions, approximate solutions of the complete system of Navier-Stokes equations are constructed and the velocity characteristics of three-dimensional unsteady gas flows initiated by local heating of the underlying surface by nineteen heat sources are numerically determined.

Calculation of thermodynamic characteristics of gas flows in concentrated fire vortices

The article presents the results of numerical simulation of gas flows in free fire vortices. The fundamental possibility of physical modeling of the occurrence of concentrated fire vortices is presented in a series of experimental studies carried out at the Joint Institute for High Temperatures of the Russian Academy of Sciences. In the model of a compressible continuous medium for the complete system of Navier-Stokes equations, an initial-boundary-value problem is proposed that describes complex three-dimensional unsteady flows of viscous compressible heat-conducting gas in ascending swirling heat fluxes. Using explicit difference schemes and the proposed initial-boundary conditions, approximate solutions of the Navier-Stokes system of equations are constructed and the thermodynamic characteristics of three-dimensional unsteady gas flows are numerically determined. The calculation results showed that in the process of formation of fiery vortices, it is formally possible to distinguish several stages. The calculations of the thermodynamic characteristics of gas flows during heating of the underlying surface by several local sources showed that the selected mathematical model under the corresponding initial and boundary conditions allows numerical experiments to describe the arising of complex unsteady three-dimensional flows.

Saturn's North Polar Vortex Structure Extracted From Cloud Images by the Optical Flow Method

AbstractThe paper presents velocity fields with ~3‐km spatial resolution of Saturn's north polar vortex (NPV) retrieved using the optical flow method from a sequence of polar‐projected cloud images captured by the Imaging Science Subsystem camera on board NASA's Cassini spacecraft. The fields of the velocity magnitude, velocity variation, relative vorticity, divergence, and second invariant are determined to characterize the flow structures of the inner core of the NPV. The mean zonal and mean meridional velocity profiles of the NPV are compared with previous measurements. We also describe the relevant details of application of the optical flow method to planetary cloud‐tracking wind measurements. The mean zonal velocity profile is consistent with the previous measurements using correlation image velocimetry methods. The small but significant meridional velocity corresponds to outwardly spiraling streams observed in the region near the north pole (NP). The concentrated vorticity and second invariant within 1° planetographic latitude of the NP indicate strong rotational motion of the fluid. An analysis is presented to explore a possible physical origin of the observed spiraling node at the NP.

Численное моделирование сложных течений газа в концентрированных огненных вихрях

This article presents the results of numerical simulation of free fire vortices arising in laboratory conditions. The authors demonstrate the possibility of obtaining such concentrated fire vortices in a series of experimental studies conducted under the supervision of A. &amp;nbsp;Yu. &amp;nbsp;Varaksin, a corresponding member of the Russian Academy of Sciences, at the Joint Institute for High Temperatures of the Russian Academy of Sciences.&lt;br&gt; The authors propose to consider the analytical and numerical studies of arising complex swirling gas flows during local heating of a metal underlying surface by several sources from the point of view of gas dynamics. When considering complex flows of a heating gas as a motion of a viscous, heat-conducting, and compressible continuous medium, the complete system of Navier&amp;nbsp;— Stokes equations is used. The proposed initial-boundary conditions made it possible to numerically determine the main gas-dynamic characteristics of the resulting three-dimensional and unsteady gas flows in free fire vortices.&lt;br&gt; The calculation results showed that during the formation of fiery vortices, several stages are distinguished in their development. The first stage is characterized by the occurrence of local gas flows diverging in the radial direction from the heating regions. The second stage is accompanied by the formation in the regions of the location of the heating sources of local vortices with opposite spin directions. The third stage is characterized by the fact that from smaller vortices due to the intense influx of external air a common large thermal vortex is formed, which receives a positive twist under the influence of the Coriolis force. At the fourth stage, with an increase in the rotation speed, a decrease in the vertical dimensions of the thermal vortex and its decay into several small ones is observed. Thus, the completion of the life cycle of one concentrated vortex is replaced by the formation of a new one. For the initial parameters, the lifetime of the concentrated thermal vortex is about one minute.

Computational Fluid Dynamics-Based Throughflow Analysis of Transonic Flows in Steam Turbines

Abstract A computational fluid dynamics (CFD)-based throughflow solver is applied to the meridional analysis of low-pressure steam turbine modules. The throughflow code inherits its numerical scheme from a state-of-the-art CFD solver (TRAF code) and incorporates real gas capabilities, three-dimensional flow features, and spanwise mixing models. Secondary flow effects are introduced via a concentrated vortex model. Tip gap and shroud leakage effects are modeled in terms of source vectors in the system of governing equations. The impact of part-span shrouds and snubbers are accounted for, on a local basis, through suitable body force fields. The advection upstream splitting method (AUSM+-up) upwind strategy has been adopted as a basis to construct a numerical flux scheme explicitly suited for throughflow applications. The original formulation has been adapted to handle real gas flows and to embed the treatment of body force fields in a fully consistent framework. The capability of the procedure is assessed by analyzing the low-pressure modules of two large steam turbines designed and manufactured by Ansaldo Energia. These modules include rotor tip shrouds and part-span snubbers and feature supersonic flow and large blade twist. Throughflow predictions in terms of main performance figures and radial distributions of flow quantities are compared with experimental data and 3D steady viscous analyses. It will be shown how the proposed CFD-based throughflow model can be fruitfully used in the early stages of the design as it delivers predictions of comparable accuracy with 3D CFD analyses at a fraction of the computational time.