Rib Case Research Articles

Case series on resection of symptomatic bifid ribs: A successful and safe treatment option

IntroductionBifid ribs are a type of, generally asymptomatic, congenital chest wall abnormality. However, patients sometimes complain about chronic chest pains, deformities and respiratory difficulty. There is limited literature regarding treatment of symptomatic bifid ribs. We present the results of two cases of symptomatic bifid ribs causing intercostal nerve impingement who underwent surgery. Presentation of caseTwo patients aged 22 and 33 presented to the outpatient clinic with chronic chest pains. After physical examination and 3D CT-scans they were diagnosed with intercostal nerve impingement caused by a bifid rib. Both patients underwent surgery to resect the upper arch of the bifid rib. Upon follow-up nine and seven months post-operatively patients reported complaints had been completely resolved and follow-up was ended. DiscussionAlthough bifid ribs are generally asymptomatic they can sometimes cause intercostal nerve impingement. These cases demonstrate that these symptoms might only start after experiencing minor trauma or a growth spurt. Intercostal nerve blockades might me a useful tool in diagnostic work-up to confirm the diagnosis. ConclusionResection of symptomatic bifid ribs is a safe and viable treatment option.

Proposed formulas for pillar stress estimation in a regular room-and-pillar pattern

Room-and-pillar mining is one of the oldest and most widely employed underground mining methods worldwide, while in recent years it has also been used for civil engineering projects and applications. The pillar design process is quite straightforward, requiring the assessment of two key elements, namely the pillar's strength and the anticipated loading imposed on it. Lots of research work has been elaborated for the estimation of pillars' strength and the main parameters associated with it, while, on the other hand, in terms of the loading the Tributary Area Theory (TAT) has been traditionally and successfully used as the dominant methodology to assess the post-mining pillar induced stresses. This paper focuses primarily on decoding the pillar loading regime by analyzing the identifying the stresses imposed to them through the use of modern computational tools offered by 2D and 3D numerical analyses, over a series of pillars' type (square, ribs), configurations and initial virgin stress fields. This allows for the development of a benchmarking framework that showcase the differences in the stress conditions and reveal the over-conservative behavior of TAT. More importantly though, it allowed for the expression of two (2) general analytical formulae for the direct estimation of the average vertical elastic stresses on pillars, both for the case of rib & square pillars layout; the most typical patterns applied in this method. They aim at providing an easy to use and more accurate estimation of the pillar stress - as compared to TAT - in alignment with the results obtained from numerical analyses. Thus, with the proposed formulas, the time-consuming numerical process needed for preliminary pillars' dimensioning is tackled in a swift and effective manner.

Numerical study of cooling performance and flow characteristics of film hole-broken rib composite structure with squealer tip

The gas turbine blade tip might face substantial heat loads because of leakage flow between the blades and the casing. For blade tip cooling, a composite cooling structure with film holes and broken ribs is first used on GE-E3 blade in this work. The flow and cooling characteristics of the innovative structure are studied by numerical simulation under various blowing ratio (BR) conditions. Meanwhile, the impact of modifying both the rib angle and the rib height on the adiabatic film cooling effectiveness (AFCE) at the tip of the squealer is analyzed. According to the results, adding rib structures to the squealer tip can effectively regulate the paths of cavity vortices and kidney-shaped vortex pairs (KVP) at the tip. As a result, the averaged AFCE at the blade tip is improved. The notch pressure-side broken rib structure has good aerothermal performance, and the highest AFCE at BRs of 0.50, 1.00, and 1.50 basically occur under the “R60-100 %” condition (R60 refers to the rib structure of 60°, and 100 % is the ratio of rib height to notch depth), and the corresponding AFCE are 27.71 %, 26.00 %, and 32.47 % higher than those of the no-rib case, respectively. The corresponding AFCE increased by 27.71 %, 26.52 %, and 32.47 %, respectively, compared to the no-rib condition. The highest AFCE at a BR of 1.50 occurs at “R75-70 %“, which is a 38.20 % increase in AFCE compared to the no rib case. The improvement in AFCE is due to the difference in the flow of the cooling jets, which are subject to cavity vortices at different BRs. The analysis shows that the addition of ribs disrupts the formation of KVPs and weakens the influence of the cavity vortex, thus reducing the low AFCE region at the lower end of the tip groove and increasing the AFCE. However, due to the blocking effect of the ribs, the pressure loss at the blade tip is elevated. The proposed blade tip cooling structure is expected to provide new ideas for the next generation of advanced gas turbine cooling designs.

Numerical Study on Flow Field and Heat Transfer Enhancement in a Cooling Channel With Novel Ribs Based on Battery Thermal Management System

Turbulent flow and heat transfer characteristics in a cooling channel with novel ribs have been numerically studied to improve thermal efficiency inside future electric vehicle batteries. In this study, the essential ratios of channel length, rib height, and rib pitch were all set to 6.67, 0.13, and 8.66, respectively. The realizable turbulent kinetic energy - epsilon model was used for the numerical simulation work under the Reynolds number varied from 10,000 to 50,000. The results showed that the heat transfer enhancement on a surface depended on the secondary flows due to the ribs. The enhancement of the wavy-winglet rib was approximately 9.8%−32% compared to other rib cases. Nevertheless, the improved heat transfer came at the expense of a higher pressure penalty. Above 29.7% of the friction factor for the wavy-winglet rib was obtained, compared to orthogonal ribs. In addition, the wavy-winglet rib gave the best thermal-hydraulic performance of the designs explored.

17 years' experience of surgical management of thoracic outlet syndrome at a district general hospital.

Thoracic outlet syndrome (TOS) is caused by compression of the neurovascular structures passing through the thoracic inlet. It is categorised into three subtypes: neurogenic TOS (NTOS), venous TOS (VTOS) and arterial TOS (ATOS). This study evaluates the outcomes of patients who underwent first rib resection (FRR) for TOS during a period of 17 years at a single district general hospital. Retrospective review of patient notes of individuals treated with FRR from August 2004 to August 2021. A total of 62 FRRs were performed on 51 individual patients. Indications for FRR included 42 NTOS (68%), 6 VTOS (10%) and 14 ATOS (23%). Thirty-four patients (64%) were female and the mean age at time of surgery was 39 years (range 27 to 64 years). Eleven patients (21%) underwent bilateral FRR and seven cases of cervical ribs were observed. The mean time from initial symptoms to diagnosis was 18 months (range 2 to 60 months). Overall, outcomes after surgery were positive across all subtypes of TOS. Based on Derkash's classification, 52 patients (84%) reported excellent/good, 8 (13%) reported fair and 2 (3%) reported poor resolution of symptoms at 6 month follow-up. Complications included four (9%) pneumothorax, two (4%) wound infections, two (4%) haematoma, one (2%) haemothorax, three (5%) phrenic nerve complications and one (2%) brachial neuropraxia. FRR for TOS can be performed safely and effectively in a district general hospital environment with excellent patient clinical outcomes.

Numerical Study of Endwall Modification with Micro-Scale Ribs in a Turbine Cascade

A novel modification method, the ‘micro-scale’ rib, is proposed to expand cooling coverage for turbine endwalls. However, the introduction of the rib will inevitably affect the flow in the near-wall region. Therefore, the variation in the flow pattern for the traditional model of secondary flow needs further exploration. In this paper, to gain a clearer understanding of the micro-scale rib, the original endwall and three types of ribbed endwalls were adopted to numerically present the detailed flow, film cooling, and heat transfer information for the endwall surface and phantom cooling on the suction side (SS) of the blade. The Ansys code CFX was utilized to solve the 3D Reynolds-averaged Navier–Stokes (RANS) equations, and the SST k-ω was selected as the turbulence model after the verification. The results show that the rib-like vortex changed the flow of the coolant and had various impacts on the cooling characteristics. Although the cooling performance of the ribbed endwall improved, it also had a negative impact on heat transfer in most cases. Compared with the original, the vertical rib cases provided optimal film cooling, with increases of 26.9% and 17.4% for rib spacing values of 8 mm and 10 mm, respectively, with little difference in heat transfer (less than 1%). In addition, the horizontal rib cases presented the worse performance for both film cooling and heat transfer, which indicates that the rib layout should consider a mainstream flow direction for future designs.

4E analysis of a new design heat sink for cooling a bifacial photovoltaic system using PCM and ribs

PV cell cooling is essential to prevent it from overheating and save its electrical efficiency from decreasing. In addition, the bifacial PV cell is more suited for small-area applications. However, there is a big challenge in cooling the bifacial PV cell surface due to the bifacial PV collects solar radiation from both the top and bottom sides. Therefore, a new heat sink of the bifacial PV system is numerically and experimentally studied. The proposed bifacial system consisted of 2 mono-facial PV cells, phase change material (PCM), and 2 aluminum plates. The PCM (paraffin wax) and the proposed arrangement of 8 ribs in the aluminum plates are used to decrease the cell temperature and improve the electrical performance of the system. The ribbed case (2PV-PCM-ribs) is compared to the smooth case (2PV-PCM-smooth) to detect the enhancement due to the ribs. The energy, exergy, economic, and enviro-economic (4E) analysis is established between the 2PV-PCM-ribs system and the bifacial system (without cooling). The outcomes explained that the electrical efficiency and the output power per unit area of the 2PV-PCM-ribs system are higher than the bifacial system (without cooling) by a significant value. The highest difference value in electrical efficiency and output power are 1.6 %, and 27.21 W/m2, respectively, which occurred at 195 min. The electricity generation cost for the 2PV-PCM-ribs is 0.07679, 0.077932, and 0.092782 $/kWh, at a lifetime of 10, 15, and 20 years, respectively, compared to 0.07717, 0.78322, and 0.93246 $/kWh, in the bifacial system (without cooling).

Enhancing the bifacial PV system by using dimples and multiple PCMs

According to the world's energy needs, the demand for bifacial photovoltaic (BPV) modules and their uses is rising quickly. So, the present study aims to design a bifacial PV-PCMs system consisting of two mono-facial PV cells, a ribbed aluminum plate, and multiple PCMs. Varying melting points among the multiple PCMs as well as the ribbed aluminum plates were used to enhance the PV cells' electrical and thermal performance. The bifacial PV-PCMs system was studied in three cases: firstly, a smooth unit with a single PCM (RT-35), second, a ribbed unit with multiple PCMs (RT-35, and RT-27), and finally, a bifacial case without cooling to get the optimum design. Data from the literature and the numerical model were in excellent agreement. A numerical investigation was done into the cell temperature and the system's electrical efficiency at different solar radiation (800, 1000, and 1200 W/m2). The results concluded that, in the ribbed case with multiple PCMs, the top cell electrical efficiency increased by 0.5 % compared to the smooth case with a single PCM. Besides that, the cell temperature is decreased by a significant value of roughly 13 °C in the proposed system compared to the bifacial cell without cooling. The cell electrical efficiency for the ribbed unit with multiple PCMs is roughly 16.68 % compared to 15.5 % in the bifacial case without cooling. The proposed design is suggested for future bifacial PV-PCMs systems for roof and small land applications.

Direct Numerical Simulation of Thermal Turbulent Boundary Layer Flow over Multiple V-Shaped Ribs at Different Angles

Direct numerical simulations (DNSs) of spatially developing thermal turbulent boundary layers over angle-ribbed walls were performed. Four rib angles (γ=90°,60°,45° and 30°) were examined. It was found that the 45° ribs produced the highest drag coefficient, whereas the 30° ribs most improved the Stanton number. In comparison to the transverse rib case, streamwise velocity and dimensionless temperature in the V-shaped cases significantly increased in the near wall region and were attenuated by secondary flows further away from the ribs, which suggested a break of the outer-layer similarity in the scenario presented. The surprising improvement of heat transfer performance in the 30° rib case was mainly due to its large dispersive heat flux, while dispersive stress reached its peak value in the 45° case, emphasizing the dissimilarity in transporting momentum and heat by turbulence over a ribbed surface. Additionally, by calculating the global and local Reynolds analogy factors, we concluded that the enhancement in heat transfer efficiency was attributed to an increasing Reynolds analogy factor in the intermediate region as the rib angle decreased.

Conjugate natural convection along regularly ribbed vertical surfaces: A homogenization-based study

Natural convection heat transfer from periodically ribbed vertical surfaces is targeted for upscaling, incorporating the analysis of thermal conduction through the microscale ribs. Asymptotic homogenization theory is employed, considering the steady conjugate heat transfer problem, to formulate second-order accurate effective conditions for velocity and temperature at a fictitious plane surface, beyond which the macroscale behavior of the flow is computed. This allows to avoid the numerically expensive resolution of fields within and through the microstructured corrugations. For the streamwise velocity component, the no-slip boundary condition is corrected at first order (in terms of a small parameter ϵ , ratio of microscopic to macroscopic length scales) by the classical Navier-slip condition plus a buoyancy term, while the gradient of the normal stress appears at second order together with a temperature-gradient term. The temperature at the virtual boundary deviates from the uniform value at the baseplate; the thermal slip is described via a first-order temperature-gradient term with a coefficient depending on rib geometry and thermal conductivity. Different case studies are conducted on the case of transverse square ribs, varying the density of the pattern and the rib-to-fluid thermal conductivity ratio, to provide extensive validation of the model against full feature-resolving simulations. Beyond the validation phase, a better understanding of the effects of different parameters on the heat transfer performance is pursued. The presence of ribs is found to decrease the overall heat transfer rate from the surface, and this deterioration is only partially alleviated by raising the thermal conductivity of the ribs. Increasing the number of conducting ribs on the hot surface has a complex, non-monotonic effect on the heat transfer rate, unlike the case of adiabatic ribs where the average Nusselt number decays monotonically. The performance of low-thermal-conductivity elements (e.g. wooden ribs) may considerably differ from that of perfectly adiabatic ones.

A Case of Extra Cervical Rib

A Case of Extra Cervical Rib

Heat Transfer in a Rotating, Blade-Shaped, Two-Pass Cooling Channel With Various 45-Deg Rib Turbulators and a Tip Turning Vane

Abstract This work experimentally studied a rotating, blade-shaped, two-pass cooling channel with various 45-deg rib turbulators and a tip-turning vane. The first passage of the cooling channel has an aspect ratio (AR) = 4:1 with the coolant moving radially outward. After a 180-deg blade-shaped tip turn, the coolant flows radially inward into the second passage with an AR = 2:1. The first and second passages are oriented at 50 deg and 105 deg from the rotation direction, respectively. In the tip-turn portion, a tip-turning vane with an oval cross section connects the mid-lines of the two passes. Two orientations of 45 deg angled ribs were considered in this work: unusual and criss-cross. The ribs have a profiled cross section and were placed in-line (P/e = 10, e/H = 0.16) on the leading and trailing surfaces of the channel. Five inlet Reynolds numbers (10,000–45,000) and five rotational speeds (0−400 rpm) were considered in this study, with a maximum rotation number of Ro = 0.38 achieved in the first pass. The results showed that the effect of the turning vane on heat transfer and pressure loss for the 45-deg unusual rib case was insignificant. The overall heat transfer for the criss-cross rib case was slightly increased by the turning vane. For pressure loss, the turning vane provided approximately an 8% reduction in the 45-deg criss-cross rib case, which was the highest in the rib cases. The 45-deg criss-cross ribs presented the highest thermal performance with the turning vane.

Film cooling characteristics of trench film hole fed by the internal cross-flow

The paper describes the film cooling characteristics of the trench film hole fed by the internal cross-flow. Three internal cross-flow cases are investigated by using numerical simulations. Results show that the main flow structures of the smooth and 45° rib cases feature helical and asymmetrical, and that of the 135° rib case is straight and symmetrical. When M = 0.5, the film cooling effectiveness η of the 135° rib case is the highest at two cross-flow Reynolds numbers. As [Formula: see text] increases to 1.0, the η of the 135° rib case at Rec = 100,000 is the highest. When [Formula: see text] = 2.0, interestingly, the highest η is achieved by the 45° rib case at Rec = 100,000. The discharge coefficient and total pressure loss coefficient increase with M for the three cases. The discharge coefficient of the 135° rib case is the highest, whereas that of the 45° rib case is the lowest. And the discharge coefficient at Rec = 100,000 is lower than that at Rec = 50,000 because the blockage is more serious at Rec = 100,000, while the total pressure loss coefficient at Rec = 100,000 is higher than that at Rec = 50,000. When Rec = 50,000, the 135° rib case exhibits a higher heat transfer coefficient HTC than the smooth case, while the area-averaged HTC of the 45° rib case depends on the M. When Rec = 100,000, the area-averaged HTC of the 45° rib case is always highest while that of the 135° rib case is always lowest. In addition, the net heat flux reduction ( NHFR) is mainly affected by the η and is more sensitive to the cross-flow at high Rec and low M.

Heat Transfer in a Rotating Blade-Shaped Two-Pass Channel with a Turning Vane

The effect of adding a tip turning vane on the heat transfer and pressure loss of a blade-shaped two-pass cooling channel was experimentally investigated in this work. In the first passage with an aspect ratio (AR) of , the coolant traveled radially outward to a 180 deg blade-shaped turn. After the turn, the coolant flowed radially inward in the second passage with . The cooling channel was positioned such that the first and second passes were angled 50 and 105 deg from the direction of rotation, respectively. The turning vane was designed with an oval cross section to connect the midlines of the two passages. A 45 deg angled ribbed case (inline, ) was studied in addition to the smooth surface case. The Reynolds number ranged from 10,000 to 45,000 in the first pass and 16,000 to 73,000 in the second pass. In this study, five rotational speeds (0–400 rpm) were considered, and the maximum inlet rotation number was . The results showed that the turning vane decreases both heat transfer and pressure loss in the cooling channel. The average overall heat transfer for the entire channel was reduced 6 and 4% by the turning vane in the smooth and ribbed cases, respectively. However, with the presence of the turning vane, the tip wall heat transfer was increased in the range of 10–20% in both the smooth and ribbed cases. The rotational effect on heat transfer was found to be reduced with the presence of the vane. On the other hand, the turning vane provided 10 and 5% pressure loss reductions in the smooth and ribbed cases, respectively.

Impact of Surface Roughness on Flow Physics and Entropy Generation in Jet Impingement Applications.

In this paper, a numerical investigation was performed of an air jet incident that normally occurs on a horizontal heated plane. Analysis of flow physics and entropy generation due to heat and friction is included using a simple easy-to-manufacture, surface roughening element: a circular rib concentric with the air jet. This study shows how varying the locations and dimensions of the rib can deliver a favorable trade-off between entropy generation and flow parameters, such as vortex generation and heat transfer. The performance of the roughness element was tested at three different radii; R/D = 1, 1.5 and 2, where D was the jet hydraulic diameter and R was the radial distance from the geometric center. At each location, the normalized rib height (e/D) was increased from 0.019 to 0.074 based on an increment of (e/D) = 0.019. The jet-to-target distance was H/D = 6 and the jet Reynolds number (Re) ranged from 10,000 to 50,000 Re, which was obtained from the jet hydraulic diameter (D), and the jet exit velocity (U). All results are presented in the form of entropy generation due to friction and heat exchange, as well as the total entropy generated. A detailed comparison of flow physics is presented for all ribs and compared with the baseline case of a smooth surface. The results show that at higher Reynolds numbers, adding a rib of a suitable height reduced the total entropy () by 31% compared to the no rib case. In addition, with ribs of heights 0.019, 0.037 and 0.054, respectively, the entropy generated by friction () was greater than that due to heat exchange () by about 42%, 26% and 4%, respectively. The rib of height e/D = 0.074 produced the minimum St at R/D = 1. As for varying R/D, varying rib location and Re values had a noticeable impact on , and (). Placing the rib at R/D = 1 gave the highest total entropy generation () followed by R/D = 1.5 for all Re. Finally, the Bejan number increased as both rib height and rib location increased.

A homogenization approach for buoyancy-induced flows over micro-textured vertical surfaces

Asymptotic homogenization is employed to formulate upscaled effective boundary conditions at a smooth virtual surface for a natural-convection flow over a periodically roughened vertical wall, to bypass the expensive numerical resolution of flow and temperature fields near and within wall corrugations. Microscale problems are found by expanding near-wall variables in terms of a small parameter $\epsilon$ , the ratio between the microscopic and the macroscopic length scales. The expressions of the upscaled velocity and temperature boundary conditions are provided up to second-order accuracy in $\epsilon$ . The case of transverse square ribs is considered as a representative example. The classical Navier-slip condition for the streamwise and the spanwise velocity components is modified at second order by the gradient of the normal stress and the time derivative of the shear stress. The streamwise slip velocity is additionally corrected by a buoyancy term at first order and a temperature-gradient term at second order. The normal velocity at the virtual surface appears only as a second-order transpiration condition. A Robin-like condition for the temperature is found, where the wall temperature is corrected with a temperature-gradient term representing thermal slip. The accuracy levels and the applicability range of the effective conditions to mimic the macroscopic flow behaviour are investigated under laminar flow conditions, in comparison with results of full feature-resolving simulations. A formal validity limit for the approximation is sought in terms of a single accuracy criterion ( $C$ ), which combines the effects of the Grashof number and the ribs’ density. The introduced model is further tested on different rib geometries.

Effect of various configurations of permeable ribs on thermal performance of solar air heater as source of clean energy

Solar air heater (SAH) ducts have poor thermal efficiency, which can be improved by introducing ribs. This study is focused on the numerical investigation of heat transfer and pressure drop of a permissible ribbed SAH duct. The flow domains for three different permissible rib geometries, i.e. horizontal slit, 30° inclined slit and 30° inclined split slit, were analysed. Different turbulence models based on two equations were compared with the experimental results for the solid rib model. The realisable, k-ε turbulence model obtained the less error of enhancement heat transfer when compared with the experimental work for solid rib. An increase in heat transfer was noted for permissible rib geometry due to secondary vortices. An increase of 12.4%, 7.4% and 1.6% was observed in average heat transfer for horizontal, 30° inclined slit and 30° inclined split slit configurations for the Reynolds number value of 12800, respectively. Inclined split slit gave the maximum friction factor when compared to other permissible rib cases. An improvement of 14%, 8.6% and 3.3% was observed in thermal performance for 30° inclined split, 30° inclined and horizontal slit at the Reynolds number value of 12800.

Study on film cooling for aero-engine turbine endwalls with various small-scale surface structures

In this study, a novel endwall modification by adding small-scale ribs onto a turbine endwall surface is proposed to reduce thermal loads on the endwall. The small-scale ribs are positioned in a streamline-curved and an axially-straight array patterns and, square and triangular shapes are imposed to the cross section of the ribs. The feasibility of improving purge air cooling by the ribs is investigated by using well-validated computational fluid dynamics (CFD) methods. Comprehensive comparisons of cooling performance among the ribbed endwall cases are made by examining cooling effectiveness, heat transfer, and aerodynamic losses. Detailed flow topologies are presented to reveal flow mechanisms involved in the actions of the ribs within the turbine passage flow. Particularly, secondary-order effects of the ribs on the turbine airfoil surfaces are also documented, which is expected to provide three-dimensional boundary conditions for the turbine aerodynamic and thermal analyses. Comparisons between the ribbed endwall cases and a smooth endwall case show that the endwall modification by adding small-scale ribs is effective in reducing thermal loads on the endwall via enhancing cooling effectiveness and, in some cases, reducing heat transfer levels. The thermal load reduction can be further improved by increasing purge air flow ratio. However, as additional vorticities are introduced by the ribs, slight aerodynamic penalty is generated. Among the four rib cases, the straight triangular-shaped rib case has the lowest overall cooling performance for the endwall. Additionally, secondary-order cooling effects are visible on the airfoil suction surface for all rib cases but only the straight rib cases can generate additional purge air coverage on the airfoil pressure surface, without significantly changing pressures in that region. This work offers a new option of thermal management techniques for the turbine endwall and the results provide guidelines regarding endwall modifications of such sort.

Incidence and Clinical Implications of Cervical Rib: A Retrospective Study

Introduction: Cervical ribs are an additional rib, which arise from the costal element of the seventh cervical vertebra. Incidence varies from 0.58-6.2%, incidentally detected on radiographs, but when enlarged can lead to various vascular and neurological symptoms. When it is of sufficient length it can compress the neurovascular bundle leading to Thoracic Outlet Syndrome (TOS) causing vascular and neurological symptoms. Aim: To determine the incidence and morphology of cervical rib in a convenient sample. Materials and Methods: A retrospective observational study was done in 650 radiographs (356 males and 294 females) from January 2016 to January 2019 and the study was conducted at ESIC Medical College and PGIMSR, Chennai, Tamil Nadu, India, and the data was analysed for the incidence and morphology of cervical ribs. Results: Incidence of cervical ribs in females (1.7%) was higher than males (1.12%). In the present study, incidence of cervical ribs was 1.38%, we observed there were seven cases of bilateral cervical ribs and two cases of unilateral cervical rib. Morphologically, cervical ribs had head, neck and tubercle and articulated posteriorly with transverse process and no other significant morphological variations were seen. Conclusion: Knowledge regarding incidence of cervical ribs and other rib anamolies assists the radiologist and surgeons in early diagnosis and management of symptomatic patients in order to avoid neurovascular complications.

Direct numerical simulation of turbulent duct flow with inclined or V-shaped ribs mounted on one wall

In this research, highly disturbed turbulent flow of distinct three-dimensional characteristics in a square duct with inclined or V-shaped ribs mounted on one wall is investigated using direct numerical simulation. The turbulence field is highly sensitive to not only the rib geometry but also the boundary layers developed over the side and top walls. In a cross-stream plane secondary flows appear as large longitudinal vortices in both inclined and V-shaped rib cases due to the confinement of four sidewalls of the square duct. However, owing to the difference in the pattern of cross-stream secondary flow motions, the flow physics is significantly different in these two ribbed duct cases. It is observed that the mean flow structures in the cross-stream directions are asymmetrical in the inclined rib case but symmetrical in the V-shaped rib case, causing substantial differences in the momentum transfer across the spanwise direction. The impacts of rib geometry on near-wall turbulence structures are investigated using vortex identifiers, joint probability density functions between the streamwise and vertical velocity fluctuations, statistical moments of different orders, spatial two-point autocorrelations and velocity spectra. It is found that near the leeward and windward rib faces, the mean inclination angle of turbulence structures in the V-shaped rib case is greater than that of the inclined rib case, which subsequently enhances momentum transport between the ribbed bottom wall and the smooth top wall.