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Einar Heiberg - One of the best experts on this subject based on the ideXlab platform.
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independent validation of four dimensional flow mr velocities and Vortex Ring volume using particle imaging velocimetry and planar laser induced fluorescence
Magnetic Resonance in Medicine, 2016Co-Authors: Johannes Toger, Marcus Carlsson, Hakan Arheden, Sebastian Bidhult, Johan Revstedt, Einar HeibergAbstract:This study aimed to: (i) present and characterize a phantom setup for validation of four-dimensional (4D) flow using particle imaging velocimetry (PIV) and planar laser-induced fluorescence (PLIF); (ii) validate 4D flow velocity measurements using PIV; and (iii) validate 4D flow Vortex Ring volume (VV) using PLIF.
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independent validation of four dimensional flow mr velocities and Vortex Ring volume using particle imaging velocimetry and planar laser induced fluorescence
Magnetic Resonance in Medicine, 2016Co-Authors: Johannes Toger, Marcus Carlsson, Hakan Arheden, Sebastian Bidhult, Johan Revstedt, Einar HeibergAbstract:PURPOSE:This study aimed to: (i) present and characterize a phantom setup for validation of four-dimensional (4D) flow using particle imaging velocimetry (PIV) and planar laser-induced fluorescence (PLIF); (ii) validate 4D flow velocity measurements using PIV; and (iii) validate 4D flow Vortex Ring volume (VV) using PLIF.METHODS:A pulsatile pump and a tank with a 25-mm nozzle were constructed. PIV measurements (1.5 × 1.5 mm pixels, temporal resolution 10 ms) were obtained on two occasions. The 4D flow (3 × 3 × 3 mm voxels, temporal resolution 50 ms) was acquired using SENSE = 2. VV was quantified using PLIF and 4D flow.RESULTS:PIV showed excellent day-to-day stability (R(2) = 0.99, bias -0.04 ± 0.72 cm/s). The 4D flow mean velocities agreed well with PIV (R(2) = 0.95, bias 0.16 ± 2.65 cm/s). Peak velocities in 4D flow were underestimated by 7-18% compared with PIV (y = 0.79x + 2.7, R(2) = 0.96, -12 ± 5%). VV showed excellent agreement between PLIF and 4D flow (R(2) = 0.99, 2.4 ± 1.5 mL).CONCLUSION:This study shows: (i) The proposed phantom enables reliable validation of 4D flow. (ii) 4D flow velocities show good agreement with PIV, but peak velocities were underestimated due to low spatial and temporal resolution. (iii) Vortex Ring volume (VV) can be quantified using 4D flow.
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Vortex Ring behavior provides the epigenetic blueprint for the human heart
Scientific Reports, 2016Co-Authors: Per M Arvidsson, Sandor J Kovacs, Johannes Toger, Rasmus Borgquist, Einar Heiberg, Marcus Carlsson, Hakan ArhedenAbstract:The laws of fluid dynamics govern Vortex Ring formation and precede cardiac development by billions of years, suggesting that diastolic Vortex Ring formation is instrumental in defining the shape of the heart. Using novel and validated magnetic resonance imaging measurements, we show that the healthy left ventricle moves in tandem with the expanding Vortex Ring, indicating that cardiac form and function is epigenetically optimized to accommodate Vortex Ring formation for volume pumping. Healthy hearts demonstrate a strong coupling between Vortex and cardiac volumes (R(2) = 0.83), but this optimized phenotype is lost in heart failure, suggesting restoration of normal Vortex Ring dynamics as a new, and possibly important consideration for individualized heart failure treatment. Vortex Ring volume was unrelated to early rapid filling (E-wave) velocity in patients and controls. Characteristics of Vortex-wall interaction provide unique physiologic and mechanistic information about cardiac diastolic function that may be applied to guide the design and implantation of prosthetic valves, and have potential clinical utility as therapeutic targets for tailored medicine or measures of cardiac health.
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Vortex Ring formation in the left ventricle of the heart analysis by 4d flow mri and lagrangian coherent structures
Annals of Biomedical Engineering, 2012Co-Authors: Johannes Toger, Sandor J Kovacs, Marcus Carlsson, Hakan Arheden, Mikael Kanski, Gustaf Soderlind, Einar HeibergAbstract:Recent studies suggest that Vortex Ring formation duRing left ventricular (LV) rapid filling is an optimized mechanism for blood transport, and that the volume of the Vortex Ring is an important measure. However, due to lack of quantitative methods, the volume of the Vortex Ring has not previously been studied. Lagrangian Coherent Structures (LCS) is a new flow analysis method, which enables in vivo quantification of Vortex Ring volume. Therefore, we aimed to investigate if Vortex Ring volume in the human LV can be reliably quantified using LCS and magnetic resonance velocity mapping (4D PC-MR). Flow velocities were measured using 4D PC-MR in 9 healthy volunteers and 4 patients with dilated ischemic cardiomyopathy. LV LCS were computed from flow velocities and manually delineated in all subjects. Vortex volume in the healthy volunteers was 51 ± 6% of the LV volume, and 21 ± 5% in the patients. Interobserver variability was −1 ± 13% and interstudy variability was −2 ± 12%. Compared to idealized flow experiments, the Vortex Rings showed additional complexity and asymmetry, related to endocardial trabeculation and papillary muscles. In conclusion, LCS and 4D PC-MR enables measurement of Vortex Ring volume duRing rapid filling of the LV.
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diastolic Vortex Ring formation in the human left ventricle quantitative analysis using lagrangian coherent structures and 4d cardiovascular magnetic resonance velocity mapping
Journal of Cardiovascular Magnetic Resonance, 2012Co-Authors: Johannes Toger, Sandor J Kovacs, Marcus Carlsson, Hakan Arheden, Mikael Kanski, Gustaf Soderlind, Einar HeibergAbstract:Summary We show that 4D magnetic resonance velocity mapping and Lagrangian Coherent Structures can be used to quantify Vortex Ring volume in the human left ventricle. Background The Vortex Ring formed in the left ventricle (LV) of the human heart duRing early diastolic inflow (corresponding to the Doppler E-wave) contains information about the normal and pathophysiologic aspects of diastole. Previous studies suggest that the volume of the Vortex Ring is an important characteristic of Vortex Ring formation. However, due to lack of quantitative methods, Vortex Ring volume has not previously been studied in the human left ventricle. The study of Lagrangian Coherent Structures (LCS) is a new flow analysis method, which for the first time enables a description of Vortex Ring shape and the quantification of Vortex Ring volume. LCS have not previously been used to quantify diastolic Vortex volume in humans. Therefore, the purpose of this study was to investigate if LCS and three-dimensional, time-resolved, three-directional phase contrast magnetic resonance velocity mapping (4D PC-MR) can be used to describe Vortex Ring shape and quantify Vortex Ring volume in the human LV. Methods
Yasuhide Fukumoto - One of the best experts on this subject based on the ideXlab platform.
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A generalized Vortex Ring model
Journal of Fluid Mechanics, 2009Co-Authors: F. Kaplanski, Sergei Sazhin, Yasuhide Fukumoto, Steven Begg, Morgan HeikalAbstract:A conventional laminar Vortex Ring model is generalized by assuming that the time dependence of the Vortex Ring thickness l is given by the relation l = a t b , where a is a positive number and 1/4 ≤ b ≤ 1/2. In the case in which a = √2v, where v is the laminar kinematic viscosity, and b = 1/2, the predictions of the generalized model are identical with the predictions of the conventional laminar model. In the case of b = 1/4 some of its predictions are similar to the turbulent Vortex Ring models, assuming that the time-dependent effective turbulent viscosity v. is equal to ll'. This generalization is performed both in the case of a fixed Vortex Ring radius R 0 and increasing Vortex Ring radius. In the latter case, the so-called second Saffman's formula is modified. In the case of fixed R 0 , the predicted vorticity distribution for short times shows a close agreement with a Gaussian form for all b and compares favourably with available experimental data. The time evolution of the location of the region of maximal vorticity and the region in which the velocity of the fluid in the frame of reference moving with the Vortex Ring centroid is equal to zero is analysed. It is noted that the locations of both regions depend upon b, the latter region being always further away from the Vortex axis than the first one. It is shown that the axial velocities of the fluid in the first region are always greater than the axial velocities in the second region. Both velocities depend strongly upon b. Although the radial component of velocity in both of these regions is equal to zero, the location of both of these regions changes with time. This leads to the introduction of an effective radial velocity component; the latter case depends upon b. The predictions of the model are compared with the results of experimental measurements of Vortex Ring parameters reported in the literature.
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curvature instability of a Vortex Ring
Journal of Fluid Mechanics, 2005Co-Authors: Yasuhide Fukumoto, Yuji HattoriAbstract:A global stability analysis of Kelvin's Vortex Ring to three-dimensional disturbances of infinitesimal amplitude is made. The basic state is a steady asymptotic solution of the Euler equations, in powers of the ratio ∈ of the core radius to the Ring radius, for an axisymmetric Vortex Ring with vorticity proportional to the distance from the symmetric axis. The effect of Ring curvature appears at first order, in the form of a dipole field, and a local straining field, which is a quadrupole field, follows at second order. The eigenvalue problem of the Euler equations, retaining the terms to first order, is solved in closed form, in terms of the Bessel and the modified Bessel functions. We show that the dipole field causes a parametric resonance instability between a pair of Kelvin waves whose azimuthal wavenumbers are separated by 1. The most unstable mode occurs in the short-wavelength limit, under the constraint that the radial and the azimuthal wavenumbers are of the same magnitude, and the limiting value of maximum growth rate coincides with the value 165/256∈ obtained by Hattori & Fukumoto (Phys. Fluids, vol. 15, 2003, p. 3151) by means of the geometric optics method. The instability mechanism is traced to stretching of disturbance vorticity in the toroidal direction. In the absence of viscosity, the dipole effect outweighs the straining field effect of O(∈ 2 ) known as the Moore-Saffman-Tsai-Widnall instability. The viscosity acts to damp the former preferentially and these effects compete with each other.
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motion and expansion of a viscous Vortex Ring part 1 a higher order asymptotic formula for the velocity
Journal of Fluid Mechanics, 2000Co-Authors: Yasuhide Fukumoto, H K MoffattAbstract:A large-Reynolds-number asymptotic solution of the Navier-Stokes equations is sought for the motion of an axisymmetric Vortex Ring of small cross-section embedded in a viscous incompressible fluid. In order to take account of the influence of elliptical deformation of the core due to the self-induced strain, the method of matched asymptotic expansions is extended to a higher order in a small parameter e =(ν/Γ ) 1/2 , where v is the kinematic viscosity of fluid and Γ is the circulation. Alternatively, e is regarded as a measure of the ratio of the core radius to the Ring radius, and our scheme is applicable also to the steady inviscid dynamics. We establish a general formula for the translation speed of the Ring valid up to third order in e. This is a natural extension of Fraenkel-Saffman's first-order formula, and reduces, if specialized to a particular distribution of vorticity in an inviscid fluid, to Dyson's third-order formula
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motion and expansion of a viscous Vortex Ring part 1 a higher order asymptotic formula for the velocity
Journal of Fluid Mechanics, 2000Co-Authors: Yasuhide Fukumoto, H K MoffattAbstract:A large-Reynolds-number asymptotic solution of the Navier{Stokes equations is sought for the motion of an axisymmetric Vortex Ring of small cross-section embedded in a viscous incompressible fluid. In order to take account of the influence of elliptical deformation of the core due to the self-induced strain, the method of matched asymptotic expansions is extended to a higher order in a small parameter =( = ) 1=2 , where is the kinematic viscosity of fluid and is the circulation. Alternatively, is regarded as a measure of the ratio of the core radius to the Ring radius, and our scheme is applicable also to the steady inviscid dynamics. We establish a general formula for the translation speed of the Ring valid up to third order in . This is a natural extension of Fraenkel{Saman’s rst-order formula, and reduces, if specialized to a particular distribution of vorticity in an inviscid fluid, to Dyson’s third-order formula. Moreover, it is demonstrated, for a Ring starting from an innitely thin circular loop of radius R0, that viscosity acts, at third order, to expand the circles of stagnation points of radii Rs(t) and ~ Rs(t) relative to the laboratory frame and a comoving frame respectively, and that of peak vorticity of radius Rp(t) as Rs R0 +[ 2 log(4R0= p t )+1 :4743424]t=R0, ~ Rs R0 +2 :5902739t=R0, and Rp R0 +4 :5902739t=R0. The growth of the radial centroid of vorticity, linear in time, is also deduced. The results are compatible with the experimental results of Sallet & Widmayer (1974) and Weigand & Gharib (1997). The procedure of pursuing the higher-order asymptotics provides a clear picture of the dynamics of a curved Vortex tube; a Vortex Ring may be locally regarded as a line of dipoles along the core centreline, with their axes in the propagating direction, subjected to the self-induced flow eld. The strength of the dipole depends not only on the curvature but also on the location of the core centre, and therefore should be specied at the initial instant. This specication removes an indeterminacy of the rst-order theory. We derive a new asymptotic development of the Biot-Savart law for an arbitrary distribution of vorticity, which makes the non-local induction velocity from the dipoles calculable at third order.
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motion and expansion of a viscous Vortex Ring part 1 a higher order asymptotic formula for the velocity
Journal of Fluid Mechanics, 2000Co-Authors: Yasuhide Fukumoto, H K MoffattAbstract:A large-Reynolds-number asymptotic solution of the Navier–Stokes equations is sought for the motion of an axisymmetric Vortex Ring of small cross-section embedded in a viscous incompressible fluid. In order to take account of the influence of elliptical deformation of the core due to the self-induced strain, the method of matched of matched asymptotic expansions is extended to a higher order in a small parameter e = (v/Γ)1/2, where v is the kinematic viscosity of fluid and Γ is the circulation. Alternatively, e is regarded as a measure of the ratio of the core radius to the Ring radius, and our scheme is applicable also to the steady inviscid dynamics.We establish a general formula for the translation speed of the Ring valid up to third order in e. This is a natural extension of Fraenkel–Saffman's first-order formula, and reduces, if specialized to a particular distribution of vorticity in an inviscid fluid, to Dyson's third-order formula. Moreover, it is demonstrated, for a Ring starting from an infinitely thin circular loop of radius R0, that viscosity acts, at third order, to expand the circles of stagnation points of radii Rs(t) and R˜s(t) relative to the laboratory frame and a comoving frame respectively, and that of peak vorticity of radius R˜p(t) as Rs ≈ R0 + [2 log(4R0/√vt) + 1.4743424] vt/R0, R˜s ≈ R0 + 2.5902739 vt/R0, and Rp ≈ R0 + 4.5902739 vt/R0. The growth of the radial centroid of vorticity, linear in time, is also deduced. The results are compatible with the experimental results of Sallet & Widmayer (1974) and Weigand & Gharib (1997).The procedure of pursuing the higher-order asymptotics provides a clear picture of the dynamics of a curved Vortex tube; a Vortex Ring may be locally regarded as a line of dipoles along the core centreline, with their axes in the propagating direction, subjected to the self-induced flow field. The strength of the dipole depends not only on the curvature but also on the location of the core centre, and therefore should be specified at the initial instant. This specification removes an indeterminacy of the first-order theory. We derive a new asymptotic development of the Biot-Savart law for an arbitrary distribution of vorticity, which makes the non-local induction velocity from the dipoles calculable at third order.
D Baldacchino - One of the best experts on this subject based on the ideXlab platform.
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verifying the blade element momentum method in unsteady radially varied axisymmetric loading using a Vortex Ring model
Wind Energy, 2017Co-Authors: W Yu, Carlos Simao Ferreira, Gijs Van Kuik, D BaldacchinoAbstract:Although the Blade Element Momentum method has been derived for the steady conditions, it is used for unsteady conditions by using corrections of engineeRing dynamic inflow models. Its applicability in these cases is not yet fully verified. In this paper, the validity of the assumptions of quasi-steady state and annuli independence of the blade element momentum theory for unsteady, radially varied, axi-symmetric load cases is investigated. Firstly, a free wake model that combines a Vortex Ring model with a semi-infinite cylindrical Vortex tube was developed and applied to an actuator disc in three load cases: (i) steady uniform and radially varied, (ii) two types of unsteady uniform load and (iii) unsteady radially varied load. Results from the three cases were compared with Momentum Theory and also with two widely used engineeRing dynamic inflow models—the Pitt-Peters and the Oye for the unsteady load cases. For unsteady load, the free wake Vortex Ring model predicts different hysteresis loops of the velocity at the disc or local annuli, and different aerodynamic work from the engineeRing dynamic inflow models. Given that the free wake Vortex Ring model is more physically representative, the results indicate that the engineeRing dynamic inflow models should be improved for unsteady loaded rotor, especially for radially varied unsteady loads. © 2016 The Authors. Wind Energy Published by John Wiley & Sons, Ltd.
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verifying the blade element momentum method in unsteady radially varied axisymmetric loading using a Vortex Ring model
Wind Energy, 2017Co-Authors: Carlos Simao Ferreira, Gijs Van Kuik, D BaldacchinoAbstract:Although the Blade Element Momentum method has been derived for the steady conditions, it is used for unsteady conditions by using corrections of engineeRing dynamic inflow models. Its applicability in these cases is not yet fully verified. In this paper, the validity of the assumptions of quasi-steady state and annuli independence of the blade element momentum theory for unsteady, radially varied, axi-symmetric load cases is investigated. Firstly, a free wake model that combines a Vortex Ring model with a semi-infinite cylindrical Vortex tube was developed and applied to an actuator disc in three load cases: (i) steady uniform and radially varied, (ii) two types of unsteady uniform load and (iii) unsteady radially varied load. Results from the three cases were compared with Momentum Theory and also with two widely used engineeRing dynamic inflow models—the Pitt-Peters and the Oye for the unsteady load cases. For unsteady load, the free wake Vortex Ring model predicts different hysteresis loops of the velocity at the disc or local annuli, and different aerodynamic work from the engineeRing dynamic inflow models. Given that the free wake Vortex Ring model is more physically representative, the results indicate that the engineeRing dynamic inflow models should be improved for unsteady loaded rotor, especially for radially varied unsteady loads.
S B Dalziel - One of the best experts on this subject based on the ideXlab platform.
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Vortex Ring induced stratified mixing mixing model
Journal of Fluid Mechanics, 2018Co-Authors: Jason Olsthoorn, S B DalzielAbstract:The study of Vortex-Ring-induced mixing has been significant for understanding stratified turbulent mixing in the absence of a mean flow. Renewed interest in this topic has prompted the development of a one-dimensional model for the evolution of a stratified system in the context of isolated mixing events. This model is compared to numerical simulations and physical experiments of Vortex Rings interacting with a stratification. Qualitative agreement between the evolution of the density profiles is observed, along with close quantitative agreement of the mixing efficiency. This model highlights the key dynamical features of such isolated mixing events.
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Vortex Ring induced stratified mixing
Journal of Fluid Mechanics, 2015Co-Authors: Jason Olsthoorn, S B DalzielAbstract:There is tantalizing evidence that some mechanically driven stratified flows tend towards a state of constant mixing efficiency. We provide insight into the energy balance leading to the constant mixing efficiency and isolate the responsible mechanism. The work presented demonstrates an important mixing efficiency regime for periodically forced externally driven stratified flows. Externally forced stratified turbulent mixing is often characterized by the associated eddies within the flow, which are the dominant mixing mechanism (Turner, J. Fluid Mech., vol. 173, 1986, pp. 431–471). Here, we study mixing induced by Vortex Rings in order to characterize the mixing induced by an individual eddy. By generating a long sequence of independent Vortex-Ring mixing events in a density-stratified fluid with a sharp interface, we determine the mixing efficiency of each Ring. After an initial adjustment phase, we find that the mixing efficiency of each Vortex Ring is independent of the Richardson number. By studying the mixing mechanism here, we demonstrate consistent features of a volumetrically confined, periodically forced external mixing regime.
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resuspension onset and crater erosion by a Vortex Ring interacting with a particle layer
Physics of Fluids, 2012Co-Authors: N Bethke, S B DalzielAbstract:This paper presents results from an experimental investigation of the interaction of a Vortex Ring with a particle layer. The flow dynamics duRing the onset of particle resuspension are analysed using particle image velocimetry, while a light attenuation method provides accurate measurements of the final eroded crater shape. This work is a continuation of the research described in R. J. Munro, N. Bethke, and S. B. Dalziel, “Sediment resuspension and erosion by Vortex Rings,” Phys. Fluids 21, 046601 (2009)10.1063/1.3083318, which focussed on the general resuspension onset dynamics and initial crater formation. Here, we analyse the velocity induced by the Vortex Ring on the particle layer surface duRing the resuspension of particles for different particle sizes, and the shape and size of the final craters that are formed by the impact of the Vortex Ring. We find that the boundary condition is characterised by a quasi-slip velocity at the particle layer surface, independent of the particle size. The particle...
Johannes Toger - One of the best experts on this subject based on the ideXlab platform.
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independent validation of four dimensional flow mr velocities and Vortex Ring volume using particle imaging velocimetry and planar laser induced fluorescence
Magnetic Resonance in Medicine, 2016Co-Authors: Johannes Toger, Marcus Carlsson, Hakan Arheden, Sebastian Bidhult, Johan Revstedt, Einar HeibergAbstract:This study aimed to: (i) present and characterize a phantom setup for validation of four-dimensional (4D) flow using particle imaging velocimetry (PIV) and planar laser-induced fluorescence (PLIF); (ii) validate 4D flow velocity measurements using PIV; and (iii) validate 4D flow Vortex Ring volume (VV) using PLIF.
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independent validation of four dimensional flow mr velocities and Vortex Ring volume using particle imaging velocimetry and planar laser induced fluorescence
Magnetic Resonance in Medicine, 2016Co-Authors: Johannes Toger, Marcus Carlsson, Hakan Arheden, Sebastian Bidhult, Johan Revstedt, Einar HeibergAbstract:PURPOSE:This study aimed to: (i) present and characterize a phantom setup for validation of four-dimensional (4D) flow using particle imaging velocimetry (PIV) and planar laser-induced fluorescence (PLIF); (ii) validate 4D flow velocity measurements using PIV; and (iii) validate 4D flow Vortex Ring volume (VV) using PLIF.METHODS:A pulsatile pump and a tank with a 25-mm nozzle were constructed. PIV measurements (1.5 × 1.5 mm pixels, temporal resolution 10 ms) were obtained on two occasions. The 4D flow (3 × 3 × 3 mm voxels, temporal resolution 50 ms) was acquired using SENSE = 2. VV was quantified using PLIF and 4D flow.RESULTS:PIV showed excellent day-to-day stability (R(2) = 0.99, bias -0.04 ± 0.72 cm/s). The 4D flow mean velocities agreed well with PIV (R(2) = 0.95, bias 0.16 ± 2.65 cm/s). Peak velocities in 4D flow were underestimated by 7-18% compared with PIV (y = 0.79x + 2.7, R(2) = 0.96, -12 ± 5%). VV showed excellent agreement between PLIF and 4D flow (R(2) = 0.99, 2.4 ± 1.5 mL).CONCLUSION:This study shows: (i) The proposed phantom enables reliable validation of 4D flow. (ii) 4D flow velocities show good agreement with PIV, but peak velocities were underestimated due to low spatial and temporal resolution. (iii) Vortex Ring volume (VV) can be quantified using 4D flow.
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Vortex Ring behavior provides the epigenetic blueprint for the human heart
Scientific Reports, 2016Co-Authors: Per M Arvidsson, Sandor J Kovacs, Johannes Toger, Rasmus Borgquist, Einar Heiberg, Marcus Carlsson, Hakan ArhedenAbstract:The laws of fluid dynamics govern Vortex Ring formation and precede cardiac development by billions of years, suggesting that diastolic Vortex Ring formation is instrumental in defining the shape of the heart. Using novel and validated magnetic resonance imaging measurements, we show that the healthy left ventricle moves in tandem with the expanding Vortex Ring, indicating that cardiac form and function is epigenetically optimized to accommodate Vortex Ring formation for volume pumping. Healthy hearts demonstrate a strong coupling between Vortex and cardiac volumes (R(2) = 0.83), but this optimized phenotype is lost in heart failure, suggesting restoration of normal Vortex Ring dynamics as a new, and possibly important consideration for individualized heart failure treatment. Vortex Ring volume was unrelated to early rapid filling (E-wave) velocity in patients and controls. Characteristics of Vortex-wall interaction provide unique physiologic and mechanistic information about cardiac diastolic function that may be applied to guide the design and implantation of prosthetic valves, and have potential clinical utility as therapeutic targets for tailored medicine or measures of cardiac health.
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Vortex Ring formation in the left ventricle of the heart analysis by 4d flow mri and lagrangian coherent structures
Annals of Biomedical Engineering, 2012Co-Authors: Johannes Toger, Sandor J Kovacs, Marcus Carlsson, Hakan Arheden, Mikael Kanski, Gustaf Soderlind, Einar HeibergAbstract:Recent studies suggest that Vortex Ring formation duRing left ventricular (LV) rapid filling is an optimized mechanism for blood transport, and that the volume of the Vortex Ring is an important measure. However, due to lack of quantitative methods, the volume of the Vortex Ring has not previously been studied. Lagrangian Coherent Structures (LCS) is a new flow analysis method, which enables in vivo quantification of Vortex Ring volume. Therefore, we aimed to investigate if Vortex Ring volume in the human LV can be reliably quantified using LCS and magnetic resonance velocity mapping (4D PC-MR). Flow velocities were measured using 4D PC-MR in 9 healthy volunteers and 4 patients with dilated ischemic cardiomyopathy. LV LCS were computed from flow velocities and manually delineated in all subjects. Vortex volume in the healthy volunteers was 51 ± 6% of the LV volume, and 21 ± 5% in the patients. Interobserver variability was −1 ± 13% and interstudy variability was −2 ± 12%. Compared to idealized flow experiments, the Vortex Rings showed additional complexity and asymmetry, related to endocardial trabeculation and papillary muscles. In conclusion, LCS and 4D PC-MR enables measurement of Vortex Ring volume duRing rapid filling of the LV.
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diastolic Vortex Ring formation in the human left ventricle quantitative analysis using lagrangian coherent structures and 4d cardiovascular magnetic resonance velocity mapping
Journal of Cardiovascular Magnetic Resonance, 2012Co-Authors: Johannes Toger, Sandor J Kovacs, Marcus Carlsson, Hakan Arheden, Mikael Kanski, Gustaf Soderlind, Einar HeibergAbstract:Summary We show that 4D magnetic resonance velocity mapping and Lagrangian Coherent Structures can be used to quantify Vortex Ring volume in the human left ventricle. Background The Vortex Ring formed in the left ventricle (LV) of the human heart duRing early diastolic inflow (corresponding to the Doppler E-wave) contains information about the normal and pathophysiologic aspects of diastole. Previous studies suggest that the volume of the Vortex Ring is an important characteristic of Vortex Ring formation. However, due to lack of quantitative methods, Vortex Ring volume has not previously been studied in the human left ventricle. The study of Lagrangian Coherent Structures (LCS) is a new flow analysis method, which for the first time enables a description of Vortex Ring shape and the quantification of Vortex Ring volume. LCS have not previously been used to quantify diastolic Vortex volume in humans. Therefore, the purpose of this study was to investigate if LCS and three-dimensional, time-resolved, three-directional phase contrast magnetic resonance velocity mapping (4D PC-MR) can be used to describe Vortex Ring shape and quantify Vortex Ring volume in the human LV. Methods
