Quantitative Flow Analysis Research Articles

Acoustic emission-based flow noise detection and mechanism analysis for gas-liquid two-phase flow

The interphase forces of gas-liquid two-phase flow produce flow noise, which contains abundant two-phase flow information, such as two-phase flow rate, flow pattern, void fraction, etc. In this study, the acoustic emission technique is utilized to measure the flow noise of gas-liquid two-phase flow quantitatively. The signal is separated and identified by the Hilbert Huang transform, the R/S analysis, and the flow noise mathematical model. The Autoregressive Integrated Moving Average (ARIMA) time series model is used to predict the energy change of bubble flow. The results show that the Hilbert Huang transform can separate the noise signal. According to the R/S analysis, IMF1-IMF3 is the interaction noise of the gas and liquid. The results show that the prediction results all fall within the 95% confidence interval. It provides new approaches for the quantitative analysis of gas-liquid two-phase flow and flow pattern transitions.

Evaluation of left ventricular function by vector flow mapping in females with systemic lupus erythematosus.

Compare the intraventricular hemodynamics of 60 females with systemic lupus erythematosus (SLE) and 61 healthy female controls, and determine cardiac function changes using vector flow mapping (VFM). To determine the effect of pulmonary artery pressure changes on left ventricular function, SLE patients were divided into a normal pulmonary artery pressure group (S1, n=24) and an elevated pulmonary artery pressure group (S2, n=36). The energy loss (EL) at each segment of the left ventricular chamber (total, basal, middle, and apical segments) during each period of the cardiac cycle (isovolumic contraction, rapid ejection, rapid filling, reduced filling, atrial contraction) was determined. The S1 group had significantly more vortices than the control group during the rapid ejection, rapid filling, and atrial contraction periods (p<0.01), and the maximum vortex areas in the S1 and S2 groups were smaller than in the control group during rapid filling and atrial contraction periods (p<0.05). Compared with the control group, the S2 group had greater EL during the systole and diastole periods (p<0.01). EL in the S1 group was significantly greater than in the control group during systole (p<0.01). During the rapid filling period, the EL was positively correlated with septal E' (r=0.784, p<0.01), and during the atrial contraction period, EL was positively correlated with septal E/e' (r=0.812, p<0.01) and A (r=0.715, p<0.01). VFM of patients with SLE can comprehensively, rapidly, and efficiently evaluate changes of myocardial mechanics and intracardiac hemodynamics and provide quantitative analysis of complex intracardiac blood flow. Key points • Vector flow mapping (VFM) is a new non-invasive ultrasound technique that evaluates changes of myocardial mechanics and intracardiac hemodynamics, and provides quantitative analysis of complex intracardiac blood flow. • This study showed that vortex and energy loss may provide more sensitive detection of cardiac dysfunction than conventional echocardiographic indexes in patients with systemic lupus erythematosus.

Age-Related Changes in Pediatric Physiology: Quantitative Analysis of Organ Weights and Blood Flows : Age-Related Changes in Pediatric Physiology.

Development of comprehensive and updated quantitative relationships between physiological parameters and age for pediatrics remains to be accomplished. Towards this goal, we have performed a thorough literature search and collected published data on organ weights and organ blood flow rates for 0-20-year-old male and female human subjects. The data were used to develop continuous relationships between physiological parameters and age, using a single form of mathematical equation. Four sets of equations (0-2years male, 0-2years female, 2-20years male, 2-20years female) for the body weight vs. age, height vs. age, and organ weight vs. age relationships and 2 sets of equations (0-20years male, 0-20years female) for organ flow rate vs. age relationship were developed. The variability of each physiological parameter was also estimated, and the equations allow simulation of a virtual population for a specific age, weight, and sex. We further compared the physiological parameters vs. age curves simulated using our equations to the existing databases (Simcyp Simulator and PK-Sim). The predicted physiological parameters were comparable between our study and the existing databases, validating our equation's utility. Additionally, we described body weight-normalized organ weights and organ blood flow rates as a function of age, to provide an insight into how the contribution of each organ towards total body weight and total blood flow changes throughout ontogenesis. The physiological parameter database and equations presented here can serve as an open source to facilitate the development of pediatric physiologically based pharmacokinetic models.

Retrospective Camera-Based Respiratory Gating in Clinical Whole-Heart 4D Flow MRI.

BackgroundRespiratory gating is generally recommended in 4D flow MRI of the heart to avoid blurring and motion artifacts. Recently, a novel automated contact‐less camera‐based respiratory motion sensor has been introduced.PurposeTo compare camera‐based respiratory gating (CAM) with liver‐lung‐navigator‐based gating (NAV) and no gating (NO) for whole‐heart 4D flow MRI.Study TypeRetrospective.SubjectsThirty two patients with a spectrum of cardiovascular diseases.Field Strength/SequenceA 3T, 3D‐cine spoiled‐gradient‐echo‐T1‐weighted‐sequence with flow‐encoding in three spatial directions.AssessmentRespiratory phases were derived and compared against each other by cross‐correlation. Three radiologists/cardiologist scored images reconstructed with camera‐based, navigator‐based, and no respiratory gating with a 4‐point Likert scale (qualitative analysis). Quantitative image quality analysis, in form of signal‐to‐noise ratio (SNR) and liver‐lung‐edge (LLE) for sharpness and quantitative flow analysis of the valves were performed semi‐automatically.Statistical TestsOne‐way repeated measured analysis of variance (ANOVA) with Wilks's lambda testing and follow‐up pairwise comparisons. Significance level of P ≤ 0.05. Krippendorff's‐alpha‐test for inter‐rater reliability.ResultsThe respiratory signal analysis revealed that CAM and NAV phases were highly correlated (C = 0.93 ± 0.09, P < 0.01). Image scoring showed poor inter‐rater reliability and no significant differences were observed (P ≥ 0.16). The image quality comparison showed that NAV and CAM were superior to NO with higher SNR (P = 0.02) and smaller LLE (P < 0.01). The quantitative flow analysis showed significant differences between the three respiratory‐gated reconstructions in the tricuspid and pulmonary valves (P ≤ 0.05), but not in the mitral and aortic valves (P > 0.05). Pairwise comparisons showed that reconstructions without respiratory gating were different in flow measurements to either CAM or NAV or both, but no differences were found between CAM and NAV reconstructions.Data ConclusionCamera‐based respiratory gating performed as well as conventional liver‐lung‐navigator‐based respiratory gating. Quantitative image quality analysis showed that both techniques were equivalent and superior to no‐gating‐reconstructions. Quantitative flow analysis revealed local flow differences (tricuspid/pulmonary valves) in images of no‐gating‐reconstructions, but no differences were found between images reconstructed with camera‐based and navigator‐based respiratory gating.Level of Evidence3Technical EfficacyStage 2

A quantitative approach for debris flow inception and propagation analysis in the lead up to risk management

This paper presents a quantitative analysis of debris flows in weathered gneiss through a methodology to identify key aspects in the lead up to risk management. The proposed methodology considers both the triggering and propagation stages of landslide using two physically based models “Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Analysis” (TRIGRS) and “Smoothed Particle Hydrodynamics” (SPH), respectively. The TRIGRS analyses provided information about the location and initial volume of potential landslides. The SPH model, adopting the initial triggering volumes as input data, allowed the back analysis of the propagation stage in terms of both main pathway and depositional area. Both models can be easily implemented over large areas for risk assessment and are able to provide interesting information for the design of risk mitigation structures. Clearly, the rigorous implementation of these models requires the use of geotechnical data obtained from in situ and laboratory tests. When these data are not available, literature data obtained for similar soils for genesis and stress history with those studied can be used. The applicability of the methodology has been tested on two debris flows which occurred in 2001 and 2005 in the province of Reggio Calabria causing extensive damage involving various lifelines. The model results have been validated with the real events, in terms of both triggering/inception areas and debris fans using two dimensionless indices (Itrig and Idep). The indices compared, respectively, the real triggering/inception area with the simulated one and the real depositional area with the numerical one. For analysed phenomena, the values of Itrig were higher than 90% while Idep assumes values higher than 70% which support the applicability of the proposed methodology.

Characterizing the scaling coefficient ω between viscous and inertial permeability of fractures

Quantitative analysis of flow in fractures is an important issue for hydrogeological and geological engineering. In this study, Forchheimer models involving viscous permeability (kv) and inertial permeability (ki) were developed for groundwater flow in different single fractures or fractured media. Based on experiments and numerical simulation, the relationship between viscous permeability and inertial permeability in a single fracture was disclosed and an important parameter ω (the scaling coefficient ω (ω = ki/kv3/2)) was characterized. The results showed: (1) the Forchheimer model fit the non-linear fluid flow in almost all types of artificial single fractures that investigated in this study; (2) inertial permeability could be predicted by viscous permeability based on the empirical quantitative model: ki=ωkv3/2\\* MERGEFORMAT(ω ≈ 108 m−2); (3) the fluctuation range of ω was related to the number of medium types, more medium types would induce a larger fluctuation range; artificial single fractures produced a smaller ω than that in natural rock fractures; ω was inversely proportional to the magnitude of the inertial effect, roughness and average aperture; the roughness element shape that caused greater turbulence effects led to larger ω; and single fractures placed vertically produced larger ω than fractures placed horizontally. In addition, the ratio of viscous permeability to inertial permeability (kv/ki) in fractures could be used as the characteristic length of Forchheimer number (Fo). By characterizing scaling factor ω, the accuracy of the quantitative model could be improved, and basis for further quantification of non-Darcy flow was established.

Polarization spectroscopy for quantitative analysis of atmospheric CO2 and air plasma flows

This article demonstrates the feasibility of polarization spectroscopy as a diagnostic tool for quantitative analysis of atmospheric pressure plasma conditions. Atmospheric pressure air and CO2 plasma flows created in a microwave-powered plasma torch are investigated. A detailed line-by-line simulation approach is employed to interpret the polarization spectra recorded in the resonator of the plasma torch. The line-by-line code for the simulation of polarization spectroscopy of O2 Schumann–Runge has been developed and verified with measurements in atmospheric pressure O2 plasma for a previous study. In this study, this simulation code for O2 absorption is used to model the polarization spectra measured in CO2 plasma and determine the inner energy distribution of the molecules for the first time. The resulting vibrational and rotational temperatures are Tvib=6115K and Trot=2660K. In order to simulate measurements in air plasma, the line-by-line code is extended to enable two-species modeling using O2 Schumann–Runge as well as NOγ absorption. The new two-species simulation approach allows for the determination of the relative number density nO2/nNO=1500±100. This paper clearly demonstrates the value of polarization spectroscopy as a quantitative measurement technique for atmospheric pressure plasma applications.

Analisis Penilaian Proyek Penanaman Modal untuk Penambahan BUS dengan Metode Net Present Value pada PO. Telaga Biru Putra Pagar Alam

This study aims to determine and analyze how the analysis of investment project assessments for bus additions using the Net Present Value at Po. TelagaBiru Putra PagarAlam ". The results of the study were based on a quantitative analysis of Operational Cash flow at Po. TelagaBiru Putra PagarAlam, namely to estimate cash flow, it is necessary to determine the estimated period / time, and this is adjusted to the life of the project for the next 5 years. Outside this period, the project is considered to be no longer profitable. Because the amount of costs will exceed income. It is predicted that in 2009 net cash inflow will be received of Rp. 542,818,018, - increased in 2010 to 569,433,437, - increased in 2011 to 583,852,265, - and increased again in 2012 to 636,454,673, - and in 2013 after determining the residual value to be Rp. 892.836.049, - these values are used in determining the Net Present Value.

In Vivo Preclinical Quantitative Flow Analysis of Arterial Anastomosis using a Microvascular Anastomotic Coupler and Clinical Application for Extracranial-to-intracranial Bypass

In Vivo Preclinical Quantitative Flow Analysis of Arterial Anastomosis using a Microvascular Anastomotic Coupler and Clinical Application for Extracranial-to-intracranial Bypass

The role of optical coherence tomography angiography in reticular pseudodrusen.

To investigate the changes in retinal and choriocapillaris vessel density (VD) in patients effected by early age-related macular degeneration (AMD) and reticular pseudodrusen (RPD), using Optical Coherence Tomography Angiography (OCTA). A total of seventy-eight eyes of 78 patients (43 male, 35 female, mean age 72.61 ± 5.15) with non-neovascular AMD (38 eyes with early AMD and 40 eyes with RPD) was recruited in this observational prospective study. Forty eyes of 40 healthy subjects represented the control group. The VD was measured in superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris in different macular regions. There were no significant differences in VD of the SCP and DCP among the controls and the two study groups (p > 0.05). The VD of the choriocapillaris revealed a statistically significant reduction in early AMD and RPD groups respect to controls (p < 0.001). Furthermore, the patients with RPD showed a significantly decreased VD respect to patients with early AMD in different macular regions (p < 0.001). The quantitative analysis of retinal and choriocapillaris blood flow by OCTA provided useful information regarding the vascular changes in non-neovascular AMD patients suggesting that the choriocapillaris loss is mainly involved in the pathogenesis of RPD.

Time-resolved thermographic analysis of the near-wall flow of a submerged impinging water jet

Time-resolved infrared thermography through infrared-transparent windows provides a novel measurement approach for non-invasive quantitative analysis of near-wall fluid flows. Here, we apply this approach to study a water flow induced by an axisymmetric submerged impinging jet in the immediate vicinity of the impingement plate. The variations in thermal radiation emitted from a thin near-wall layer result from passive scalar mixing of the weakly heated jet with ambient water. We analyze the magnitudes and turbulent behavior of the thermal fluctuations captured at a frame rate of 300 Hz for various jet impingement configurations and a wide range of jet Reynolds numbers (4000–35000). The results suggest that changes in root mean square and power spectra of the thermal signal are linked to changes in mixing intensity and flow structure in the near-wall region extending up to 16 nozzle diameters from the stagnation point.

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.

Quantitative analysis of mass and energy flow in rice straw gasification based on mass and carbon balance

There have been some pilot-scale trials of the fluidized bed and its derivatives for rice and wheat straw gasification in China. Before the industrial promotion, the quantitative data is imperative in preliminary engineering and optimization. A series of experiments were performed on a bench-scale fluidized bed gasifier to obtain data in process in different heat exchange situations. The uncertainty was evaluated and the balance of carbon and mass was performed to verify the quantitative data. Based on the experimental results, the mass and energy flows were established and illustrated in Sankey diagrams. The results show that, as temperature improves from 650 °C to 800 °C, the energy proportion of gas climbs from 27.2 to 64%. When the equivalence ratio decreases, although the calorific value of gas increases from 2.7 to 4.2 MJ/Nm3, the energy proportion of gas does not change much because the gas yield decreases. Finally, the heat exchange, temperature and ER were coupled by interpolation and illustrated in a contour map.

Managing agricultural vulnerability to phosphorus scarcity through bottom-up assessment of regional-scale opportunities

Many developing countries are dependent on imported phosphorus (P) fertilizers and therefore increasingly vulnerable to scarcity of non-renewable global phosphate supplies, including short-term disruptions. A combination of participatory approach with quantitative substance flow analysis was used for identifying strategies for strengthening preparedness of regional food systems towards potential P scarcity. A P vulnerability index (PVI) – the lower its value, the higher the vulnerability (or P insecurity) – was defined on a regional scale in consultation with local stakeholders including government officials and experts and with farmers seriously affected by relevant policies and programmes. Potential mitigation and adaptation strategies were developed based on the estimated PVI and regional P flows. Regional policy planning and implementation with participatory approach are critical, because national, top-down policies may not cater to local and regional challenges and aspirations. The participatory approach offered fresh insights hitherto unidentified in top-down approaches. The study region, Sonipat in Haryana, India, is highly vulnerable to potential P scarcity (PVI of 38.68) but can theoretically reduce its P requirements by 11,574 t annually (about 85% of the current requirements) through recovery and recycling of P from human waste and by adjusting the fertilizer dose. Crop diversification combined with recycling and recovery of P and better governance can increase the PVI to 60 and above, implying adequate P security. Soil fertility, farmers' income, and access to institutional credit had the maximum impact on P vulnerability. The proposed framework can be applied in other countries to contextualize challenges related to P management and to devise strategies for building P security at regional scale.

An in-depth quantitative analysis of wind turbine blade tip wake flow based on the lattice Boltzmann method.

With the continuous increase in the total quantity and quality of wind energy used by society, the aerodynamic complexity of wind turbine impellers has also gradually increased. This requires a more accurate analysis and understanding of the aerodynamic performance of important parts of the wind turbine impeller. The blade tip vortex is undoubtedly one of the most important issues. This article used the state-of-the-art lattice Boltzmann method (LBM), combining large eddy simulation (LES) and wall-adapting local-eddy (WALE) model, to investigate the unsteady flow characteristics of the blade tip region due to impeller wake for a wind turbine. The trend of this calculation result is consistent with the experimental data, both for the axial force and the torque on the impeller. Therefore, it indicates the calculation model of LBM is reasonable and effective. The relevant in-depth results clearly showed the dynamic stability of a spiral structure will increase as operating conditions continue to advance and it is also synchronously affected by the tower wake flow structures. The fluctuation amplitude of the static pressure value on both sides of the impeller gradually decreases with time. The distribution of static pressure near the leading edge of the tip is very different for each blade due to the influences of turbulence intensity and the tower shadow effect. The random minor fluctuations of the axial force and torque both exhibit similar characteristics, and the overall torque is more sensitive to random changes in the tip vortex on the impeller surface.

Particle streak velocimetry using ensemble convolutional neural networks

This study reports an approach and presents its open-source implementation for quantitative analysis of experimental flows using streak images and Convolutional Neural Networks (CNN). The latter are applied to retrieve a length and an angle from streaks, which can be used to deduce kinetic energy and directionality (up to 180$^{\circ}$ ambiguity) of an imaged flow. We developed a quick method for generating essentially unlimited number of training and validation images, which enabled efficient training. Additionally, we show how to apply an ensemble of CNNs to derive a formal uncertainty on the estimated quantities. The approach is validated on the numerical simulation of a convenctive turbulent flow and applied to a longitutidal libration flow experiment.

Flow visualization and transient behavior analysis of luminescent mini-tufts after a backward-facing step

Luminescent mini-tufts method has been used for surface flow visualization for a long time. One major challenging point of this method is quantitative analysis of transient flows and the dynamic structures. This study is focused on the application of luminescent mini-tufts method in transient flows. A backward-facing step (BFS) is used in this analysis, which is one classic model that consists both flow separation and re-attachment processes. In this study, the instantaneous mini-tufts recognition, image averaging and tuft inclination angle/tuft angle estimation processes are introduced for the analysis of luminescent mini-tufts for the first time on backward-facing step flow (Rem = 2.0 × 105–7.9 × 105 and Reh = 1.3 × 104–5.3 × 104). Detailed transient features and characterization process for the backward-facing step model are explained in this study. The combination of optical-oil flow and hot-wire anemometry methods with luminescent mini-tufts are also shown useful to give comprehensive flow field information, including the surface flow behaviors, boundary layer, re-attachment position identification, etc. In addition, the decomposition of the luminescent mini-tufts visualization data is also conducted to give the power spectral density (PSD) and characteristic frequencies for the mini-tufts behaviors under transient fluctuating flow conditions.

Optical Coherence Tomography Angiography Compared to Fluorescein Angiography in Central Retinal Vein Occlusion

Background: Retinal vein occlusion is the second most common cause of retinal vascular disease worldwide after diabetic retinopathy. Objective: It is a prospective comparative study to evaluate the optical coherence tomography angiography appearance of superficial and deep capillary plexa in eyes with central retinal vein occlusion in comparison to conventional finding in fluorescein angiography. The study was approved by the medical ethics committee of Al-Azhar University Hospitals and a written informed consent is obtained from all patients. Patients and Methods: A total of 19 eyes of 17 patients (with a known clinical diagnosis of CRVO; any stage, any type), were recruited. All patients underwent standard ophthalmological examination together with multimodal imaging procedures including; color fundus photography, fluorescein angiography and optical coherence tomography angiography. Quantitative flow analysis of the SCP has been performed for selected 15 images of 15 eyes with CRVO versus a single eye of a normal control. Results: Optical coherence tomography angiography can qualitatively demonstrate all the macular complications of CRVO including; ischemia, capillary dilation, microaneurysms, collateral vessels, edema and intraretinal hemorrhages, with superiority to fluorescein angiography especially in the presence of retinal hemorrhages and retinal edema. OCTA with the help of the co-registered en face OCT images, can demonstrate laser scars, at the level of the choriocapillaris and can help in detecting disc edema. Statistical analysis of the incidence of the different pathological findings in CRVO, has revealed more severe affection of the deep capillary plexus than the superficial one. Conclusion: OCTA allows stratigraphic analysis of the retinal and choroidal vasculatures. It also allows performing quantitative flow analysis of the retinal vasculature providing an easily interpretable noninvasive objective tool for the management and monitoring the progression of CRVO.

ECG Gating Is More Precise Than Peripheral Pulse Gating When Quantifying Spinal CSF Pulsations Using Phase Contrast Cine MRI

To compare accuracy of spinal cerebrospinal fluid (CSF) pulsatile flow measurements at cervical, thoracic, and lumbar levels using Phase Contrast Cine MRI (PCCMRI) with retrospective electrocardiogram (recg) vs. retrospective peripheral pulse gating (rppg) gating. We scanned 10 healthy volunteers, ages 23-46 years, using external recg-gated or rppg-gated 2D PCCCMRI at 3T. Transverse scans of CSF, arteries and veins scans were at C1/C4/T1/T7/L1-L3. Data were analyzed with custom Matlab-based software, measuring CSF, arterial (descending aorta, abdominal aorta, common carotid artery, ICA, and vertebral artery) and venous (internal jugular vein and inferior vena cava) flow, velocity and region of interest area. recgPCCMRI produced less quantitative and temporal statistical variation than pcgPCCMRI when analyzing CSF flow. The instantaneous recgPCCMRI CSF flows consistently decreased craniocaudally, while the results with rppgPCCMRI were less consistent. The recgPCCMRI root mean square error values were 6.04, 6.94, 4.81, 4.49, and 4.16 for C1, C4, T1, T7, and L2, compared with 7.24, 8.97, 7.9, 7.82, and 6.68 for rppgPCCMRI. Results were independent of analysts. Summations of standard errors produced similar results. RppgPCCMRI also showed increase variability of CSF flow correlations with arteries and veins compared to recgPCCMRI. None-the-less, when recgPCCMRI is considered the reference standard, there is good correlations between rppgPCCMRI and recgPCCMRIdata sets, when averaged over cohorts of at least five subjects. Our results indicated that recgPCCMRI is more quantitatively and temporally precise than rppgPCCMRI in CSF quantitative flow analysis. Pulse-gating CSF flow results are reasonable when averaged over cohorts of at least five subjects, but subtle conclusions should be interpreted with caution.

Comparison of two accelerated 4D-flow sequences for aortic flow quantification

To compare two broadly used 4D-flow- with a 2D-flow-sequence in healthy volunteers, regarding absolute flow parameters, image quality (IQ), and eddy current correction (ECC). Forty volunteers (42 ± 11.8 years, 22 females) were examined with a 3T scanner. Thoracic aortic flow was assessed using a 3D-T2w-SPACE-STIR-sequence for morphology and two accelerated 4D-flow sequences for comparison, one with k-t undersampling and one with standard GRAPPA parallel-imaging. 2D-flow was used as reference standard. The custom-made software tool Bloodline enabled flow measurements for all analyses at the same location. Quantitative flow analyses were performed with and without ECC. One reader assessed pathline IQ (IQ-PATH) and occurrence of motion artefacts (IQ-ART) on a 3-point grading scale, the higher the better. k-t GRAPPA allowed a significant mean scan time reduction of 46% (17:56 ± 5:26 min vs. 10:40 ± 3:15 min) and provided significantly fewer motion artefacts than standard GRAPPA (IQ-ART 1.57 ± 0.55 vs. 0.84 ± 0.48; p < 0.001). Neither 4D-flow sequence significantly differed in flow volume nor peak velocity results with or without ECC. Nevertheless, the correlation between both 4D-flow sequences and 2D-flow was better with ECC; the k-t GRAPPA sequence performed best (R = 0.96 vs. 0.90). k-t GRAPPA 4D-flow was not inferior to a standard GRAPPA-sequence, showed fewer artefacts, comparable IQ and was almost two-fold faster.