P-wave Research Articles

Study on water hammer phase transition characteristics of dense/liquid phase CO2 pipeline

Under water hammer conditions, dense/liquid phase CO2 pipelines are prone to enter the phase equilibrium zone due to significant pressure fluctuations, further disrupting flow stability. At present, the research on the sudden changes in physical properties and pressure wave transmission characteristics caused by CO2 phase transition during water hammer transient process is not clear. This article uses experiments to screen the state equation suitable for CO2 phase characteristic calculation. Based on this, the characteristic line method is used to solve the one-dimensional pipeline water hammer flow process. When the water hammer pressure is lower than the saturation pressure, the corresponding gas phase fraction is solved using the isentropic principle. The results indicate that a phase transition occurs under water hammer conditions when the operating temperature is 280-300K and the operating pressure is 0.59% -4.55% higher than the saturation pressure. When a phase transition occurs, for the valve front, 1.33% gas generation will increase the pressure wave velocity by 1.67%, and for the valve rear, 0.86% gas generation will increase the pressure wave velocity by 0.61%. This study provides a basis for the safe and stable operation of CO2 pipelines.

Experimental study on hydrogen pipeline leakage: Negative pressure wave characteristics and inline detection method

This paper presents an experimental study on a potential safety system for hydrogen fuel cells. It focuses on early leakage detection and localization. This would enable effective system response to avoid the effects of catastrophic loss of containment. Experimental results are presented from a pipeline setup wherein the leak is identified utilizing inline pressure sensors and flowmeters. The investigations involve recorded data at two leak locations at different initial pressures, mass flow rates, and leak diameters. The leak detection technique is based on analysis of the negative pressure wave (NPW) intensity and propagation duration, denoted as peak-to-peak amplitude (Δh) and oscillation period (Δτ). They are extracted from filtered pressure records' first derivative (dp/dt). Δh and Δτ increase as the initial mass flow rate and leak diameter decrease. Therefore, this approach is advantageous for detecting leaks from tiny cross-sections. Δh and Δτ measured at two leak positions at different lengths from the system inlet increase at a higher initial flow rate of 1.0 g/s, but they exhibit opposite behavior at a lower rate (0.42 g/s). Increasing the sampling rate in the dp/dt-time graphs enhances the precision of leak localization. Calculation results show an effective leakage localization with an accuracy of 15 mm (2.5%). The leak flow rate during nitrogen leakage tests is about three times that of hydrogen, and it has higher Δh (about two times at 10 bar).

Feasibility analysis and parameter optimization of ultrasonic assisted electrolytic plasma polishing of small modulus gears

Precision polishing of small modulus gears is a difficult task due to the complexity of their geometry. Electrolytic plasma polishing technology as a green and efficient processing method, it can effectively decrease the friction between parts and improve the service life. However, considering the uneven distribution of gas layers on the surface of workpieces in electrolytic plasma polishing, which affects the precision of workpiece shapes after polishing, this study proposed the use of ultrasonic vibrations to generate pressure waves to improve the fluid characteristics. Comparative experiments on small modulus gear electrolytic plasma polishing with and without ultrasonic vibration were conducted. A high-speed camera was utilized to monitor the distribution of gas layers around the workpiece during the polishing process in real-time. The optical measurement methods were used to evaluate the gear precision. The results indicate that ultrasonic assistance is beneficial in improving the uniformity of the gas layers surrounding the workpiece, achieving higher gear precision, and obtaining a lower surface roughness after polishing. Through orthogonal experiments, this study analyzed the effects of various process parameters on the surface roughness of gear profiles and the uniformity of material removal after polishing. These parameters included power voltage, polishing time, workpiece immersion depth, ultrasonic frequency, and workpiece posture angle. An optimal combination of process parameters was identified. The results show that the best surface roughness and gear precision were achieved with a power voltage of 300 V, a polishing time of 4 min, a workpiece immersion depth of about 10 mm, an ultrasonic frequency of 40 kHz, and a workpiece tilt angle of 45°.

Numerical Study of the Spontaneous Ignition Mechanisms of Pressurized Hydrogen Released Inside Pipes with Different Structures

Hydrogen is considered a key clean energy carrier to achieve the global goal of carbon neutrality. But spontaneous ignition can occur when pressurized hydrogen is released into pipes, and the presence of different pipe structures will significantly affect the ignition mechanism. In this work, the effects of varied pipe structures on the shock wave propagation and spontaneous ignition characteristics are investigated by numerical simulation with the DNS-like approach, EDC combustion model, and 21-step detailed hydrogen combustion mechanism. Results show that the simulation is in well agreement with the experimental data. Five dominant spontaneous ignition mechanisms are provided depending on different pipe structures. Among all types of pipe structures investigated, contraction structures can lead to a greater increase in shock wave pressure due to more severe shock wave reflection and convergence. While enlargement structures can contribute to more mixing of hydrogen and air, causing more sufficient combustion. This study provides a comprehensive understanding and clear safety guidance to inform the practical application of hydrogen energy.

The probabilistic dependence of ship-induced waves is preserved spatially and temporally in the Savannah River (USA).

The rapid changes in the shipping fleet during the last decades has increased the ship-induced loads and, thus, their impact on infrastructures, margin protections and ecosystems. Primary waves have been pointed out as the cause of those impacts, with heights that can exceed 2m and periods around 2 minutes. Consequently, extensive literature can be found on their estimation mainly from a deterministic perspective with methods based on datasets limited to one location, making difficult their generalization. These studies propose either computationally expensive numerical models or empirical equations which often underestimate the extreme primary waves, hindering their use for design purposes. Moreover, a framework to allow the design of infrastructure under ship-wave attack based on probabilistic concepts such as return periods is still missing. In this study, a probabilistic model based on bivariate copulas is proposed to model the joint distribution of the primary wave height, the peak of the total energy flux, the ship length, the ship width, the relative velocity of the ship and the blockage factor. This model, a vine-copula, is developed and validated for four different deployments along the Savannah river (USA), with different locations and times. To do so, the model is quantified using part of the data in one deployment and validated using the rest of the data from this deployment and data of the other three. The vine-copula is validated from both a predictive performance point of view and with respect to the statistical properties. We prove that the probabilistic dependence of the data is preserved spatially and temporally in the Savannah river.

Noise Source Identification for the Unsteady Low-Pressure Turbine Flow Fields

Abstract The article presents a data processing methodology to identify the noise sources in low-pressure turbine (LPT) stages and their relative importance. Scale adaptive simulation (SAS) has been carried out on a geometry reproducing the midspan blade section of an entire LPT stage. The proper orthogonal decomposition (POD) is applied to data matrices constructed with the velocity and the pressure fields in order to distinctly extract the coherent structures responsible for velocity fluctuations and pressure waves (i.e., POD modes from the corresponding kernel), their temporal evolution and energies. The cross-correlation matrices of the pressure modes and the velocity modes reveal the degree of coupling between pressure and velocity oscillations, thus highlighting the modes linked to the same flow phenomena. The results show that the periodic vortex shedding at the stator trailing edge emits strong pressure waves, and the upstream-propagating waves reflect against the adjacent stator suction surface. The POD modes related to the rotor–stator interaction show peak amplitudes at the blade passing frequency and its harmonics and their shapes mimic the potential interaction in the stator domain and the migration of viscous wakes in the rotor domain. The POD modes with lower energy content correspond to the stochastic turbulent structures originated from the turbulent boundary layers as well as those carried by the vane and blade wakes. The biggest noise sources of the current flow fields are identified to be the von Karman vortex street downstream the stator trailing edge and the rotor–stator interaction.

EXTH-39. A BENCH-TOP MODEL FOR THE OPTIMIZATION OF ULTRASOUND PARAMETERS FOR SONODYNAMIC THERAPY OF GLIOBLASTOMA

Abstract BACKGROUND In-vitro studies have demonstrated that low frequency sound waves can interact with hemo-porphyrin molecule to induce the production of reactive oxygen species. This biophysical phenomenon can induce tumour cell death in glioblastoma cells in-vitro. The purpose of this study was to evaluate the production of reactive oxygen species and expression of apoptotic markers in glioblastoma cells in response to varying total treatment time and ultrasound power using a bench-top focused ultrasound (FUS) device. METHODS U251 cells were exposed to 5-Aminolevulenic Acid (5-ALA) at varying concentrations for up to 24 hours. The time point with peak proto-porphyrin IX (PPIX) fluorescence was established using fluorescence activated cell sorting (FACS). A transducer utilized at 0.91MHz was placed on an inverted stage with the focus targeted to the bottom of a standard 96-well cell culture plate. Pressure wave delivery was confirmed using a hydrophone. GBM cells were treated with 5-ALA alone, FUS alone, or 5-ALA + FUS and the cells were incubated for 24 hours prior to measuring ROS induction and cell death. ROS was measured using FACS with the CellROX Green Kit for Oxidative Stress Detection and Annexin-V was measured using the Dead Cell Stain Kit. RESULTS Peak fluorescence intensity for PPIX in the U251 cell line was found to be induced through incubation with 5-ALA for 24 hours with a concentration 200mg/mL. The fluorescence intensity of PPIX was found to be 313% greater in the treated group compared to the control group. Peak ROS was observed using a 0.91MHz transducer frequency for a total time of 120s with 6W average power. ROS was 61% and 66% greater in the SDT group compared to the FUS and 5-ALA group respectively. CONCLUSION Using this bench-top set up we successfully induced ROS and apoptosis in U251 cells. Establishing a reliable in-vitro model will allow us to further investigate the effects of other sonication parameters such as burst length.

QUALITATIVE ANALYSIS OF TEMPERATURE ERROR OF NEGATIVE PRESSURE WAVE METHOD FOR DETERMINING THE LOCATION OF A PIPELINE LEAK

The article is devoted to the qualitative analysis of the temperature error of the negative pressure wave method for determining the location of a pipeline leak. Recording the arrival time of the negative wave at both ends of the pipeline allows you to determine the location of a pipeline leak. In contrast to known works on this topic, this article proposes a method for qualitative analysis of the error in determining a leak location. Based on the variational optimization method, an optimal ratio of the mode indicators at which the minimum error in determining the location of a leak can be achieved is defined. A method for qualitative analysis of the error in determining the leak location using the negative pressure difference wave method is proposed. The optimal correlation of the mode functions is determined at which the minimum error in determining the leak location is achieved. An expression for estimating the relative error in determining the leak location using the negative pressure difference wave method is obtained.

Efficacy of Olmesartan/Amlodipine Single-Pill Combination on 24-h Mean Systolic Blood Pressure Measured by Ambulatory Monitoring in Non-Responders to Valsartan or Candesartan Monotherapy.

The aim of this study was to evaluate the efficacy of olmesartan/amlodipine (OLM/AML) single-pill combination (SPC) therapy using ambulatory blood pressure monitoring (ABPM) in non-responders to valsartan or candesartan monotherapy. Isolated systolic hypertension (ISH) is the most prevalent form of hypertension in middle-aged and elderly individuals. Patients aged over 55 years who did not achieve the target systolic blood pressure (SBP < 140mmHg) with valsartan 80mg or candesartan 8mg for at least 4 weeks were included. Doses were escalated from 20/5mg to 40/5mg and finally to 40/10mg of OLM/AML SPC until patients reached the target SBP. Efficacy was assessed via ABPM by comparing baseline values with those in the 12th week. Office blood pressure (OBP) and brachial-ankle pulse wave velocity (baPWV) were assessed at baseline, weeks 4, 8, and 12. Fifty-four patients (average age 64 ± 6 years; 33 males) participated. The 24-h mean BPs decreased significantly from an average of 146.2 ± 12.7/93.3 ± 9.2mmHg to 129.7 ± 14.3/83.4 ± 10.7mmHg (p < 0.001), and pulse pressures (PPs) from ABPM were reduced (p < 0.001). Additionally, significant reductions in night-time SBP standard deviations (SDs) (14.7 ± 4.7vs. 12.5 ± 3.9, p = 0.029) were observed at 12 weeks compared to baseline. OBPs significantly dropped from 151.1 ± 9.7/89.3 ± 8.3mmHg to 125.5 ± 13.8/77.8 ± 8.8mmHg after 12 weeks of SPC therapy (p < 0.001). Reductions in PPs of OBP and baPWVs were also observed. OLM/AML SPC therapy effectively reduced the 24-h mean BP, as measured by ABPM, in hypertensive patients over 55 years old who failed to achieve a target SBP (< 140mmHg) with angiotensin receptor blocker (ARB) monotherapy using valsartan 80mg or candesartan 8mg. Trial Registration: ClinicalTrials.gov identifier: NCT01713920.

Improved MER algorithm for lost circulation detection using transient pressure waves

In order to solve the difficult problem of locating the leakage layer in the bare eye well section during drilling, this study proposes a transient pressure wave well leakage detection method based on the modified energy ratio (MER) analysis. The method makes clever use of the similarity between the transient pressure waveform and the first arrival of the microseismic signal, and accurately captures the sudden change moments of the pressure wave to obtain the time difference of the signal through the MER method, and combines with the wave velocity of the pressure wave to achieve the precise location of the leakage layer. To address the problem of high noise content in transient pressure wave signals, this study proposes an improved variational modal decomposition (VMD) adaptive denoising method, which effectively removes the noise components and retains the key features of the signals to the maximum extent, and the signal-to-noise ratio of the signal after noise reduction can be up to 15.64. The experimental results show that the leaky layer localisation error of the method ranges from 0.13% to 5.30%. Under the same conditions, the accuracy of the MER localisation method is better than that of the wavelet mode maxima method, the frequency domain method and the short-time averaging/long-time averaging (STA/LTA) method, and the localisation error rate can be as low as 2.11%. The transient pressure wave well leakage detection method based on the improved MER algorithm provides a low-cost, high-precision and efficient solution for well leakage detection during drilling.

Predicting pressure buildup behind perforated plates under blast wave impact: A simplified approach

This study experimentally investigates the interaction of an incident blast wave with a perforated multiple plate array and the subsequent pressure buildup on an end wall. Experiments are conducted in a square tunnel using arrays composed of plates with varying porosities and perforation diameters positioned at different distances from the end wall. High-speed shadowgraphy and pressure measurements quantify the influence of these parameters on transmitted wave attenuation and pressure buildup on the end wall. Results demonstrate that wave attenuation and pressure buildup rates are significantly influenced by plate porosity, array length, and stand-off distance, whereas the perforation diameter has a negligible effect. A theoretical model is employed to predict the measured end wall pressure history. The model accurately predicts overall pressure history, including peak pressure and decay, for various porosities, plate numbers, and stand-off distances. Deviations between model predictions and experimental data are analyzed. Additionally, the pressure measurements reveal a power-law relationship between the transmitted wave attenuation rate and the porosity index. Notably, arrays with lower porosity, consisting of fewer plates, can effectively attenuate the transmitted wave compared to higher porosity configurations with more plates. By attenuating the peak pressure on the target wall/end wall and extending the pressure buildup time, the perforated plate arrays provide a promising approach to enhance blast protection.

An experimental investigation on the performance of a single cylinder diesel engine at various partial loads

This study investigates various partial load characteristics of a diesel engine, including brake specific fuel consumption, torque, and power, to get insight into these performances in practice. Firstly, these characteristics were experimentally examined with approximate 25, 50, 75, and 85% fuel rack settings at 900 to 2400 rpm engine speeds. Then, more operating modes were investigated to build characteristics corresponding to constant fuel quantity per engine cycle. The results indicate that the practical partial load characteristics significantly differ from the theory of full-load characteristics since the fuel quantity per cycle varies even though the rack is fixed. Especially at low loads, the fuel quantity per cycle increases enormously with engine speed due to the significant influence of pressure waves. Hence, torque and power increase continuously, making it challenging to control the engine operation. In contrast, because the reduction in fuel viscosity and pump efficiency balances the pressure wave effects at high loads, fuel quantity per cycle remains relatively constant, making the characteristics more similar to the theory. Besides, if fuel quantity per cycle is kept constant, the trends in partial load curves follow the theory, which can be approximately predicted. These findings reveal that considering fuel quantity per cycle is significant when studying diesel engine partial loads, notably at low loads. The study contributes a vital basis for further investigating and modeling the partial characteristics of diesel engines. Also, it is a crucial reference for estimating the suitable working conditions of engine-driven systems in practice.

Numerical investigation on the liquid jet and the dynamics of the near-wall cavitation bubble under an acoustic field

The dynamics of the near-wall cavitation bubble in an acoustic field are the fundamental forms of acoustic cavitation, which has been associated with promising applications in ultrasonic cleaning, chemical engineering, and food processing. However, the potential physical mechanisms for acoustic cavitation-induced surface cleaning have not been fully elucidated. The dynamics of an ultrasonically driven near-wall cavitation bubble are numerically investigated by employing a compressible two-phase model implemented in OpenFOAM. The corresponding validation of the current model containing the acoustic field was performed by comparison with experimental and state-of-the-art theoretical results. Compared to the state without the acoustic field, the acoustic field can enhance the near-wall bubble collapse due to its stretching effect, causing higher jet velocities and shorter collapse intervals. The jet velocity in the acoustic field increases by 80.2%, and the collapse time reduces by 40.9% compared to those without an acoustic field for γ = 1.1. In addition, the effects of the stand-off distances (γ), acoustic pressure wave frequency (f), and initial pressure (p*) on the bubble dynamic behaviors were analyzed in depth. The results indicate that cavitation effects (e.g., pressure loads at the wall center and the maximal bubble temperature) are weakened with the increase in the frequency (f) owing to the shorter oscillation periods. Furthermore, the maximum radius of bubble expansion and the collapse time decrease with increasing f and increase with increasing p*. The bubble maximum radius reduces by 12.6% when f increases by 62.5% and increases by 20.5% when p* increases by 74%.

Pipeline leak detection and localization based on the flow balance and negative pressure wave methods

The traditional water supply pipeline leak detection and location method has problems of false alarms, low positioning accuracy, and low stability. This paper focuses on the pipeline leak detection and location experimental platform to investigate water supply pipeline leaks, followed by simulation and experimental validation. This study integrates the mass flow balance method and pressure change inflection points to determine pipeline leaks and introduces an improved negative pressure wave method for locating leakage points. The results demonstrate that the system accurately detects pipeline leaks. The average positioning error of the improved negative pressure wave method for the leakage point is 4.76%, which has good stability and high positioning accuracy.

Assessment of arteriosclerosis based on lognormal fitting

Objective. Pulse pressure waves contain information about human physiology. There is a need for a simple, accurate way to know cardiovascular health in the clinic, so as to realize the implementation of convenient and effective early health monitoring for patients with arteriosclerosis.Approach. This study proposes an arteriosclerosis assessment method based on fitting a lognormal function, along with improving a conventional electronic sphygmomanometer. During the deflation phase of blood pressure measurement, the cuff pressure was kept constant (40 mmHg) and an additional 10 s of pulse signal was acquired. To derive the pulse pressure waveforms for a single cycle, the acquired pulse data of 101 cases were preprocessed in this study, including filtering for noise removal, onset point identification, removal of baseline drift, and normalization. In this study, an improved pulse resolution algorithm is proposed for the multimodal problem of the pulse wave, combining waveform matching and threshold setting, and finally obtaining the resolution parameters of the lognormal function with an average error less than 1.5%.Main results. According to the correlation analysis, the resolved parametersA1,W2,C2,W3, andC3were significantly correlated with brachial-ankle Pulse Wave Velocity, and the absolute correlation range in 0.17-0.53, which can be used as a reference index for arteriosclerosis. An arteriosclerosis assessment model was constructed based on the support vector mechanism, and the prediction accuracy was 91.1%.Significance. This study provides a new solution idea for the arteriosclerosis assessment method as well as the pulse resolution algorithm, which has a greater reference value.

How Do Forecast Model Biases Affect Large-Scale Teleconnections That Control Southwest U.S. Precipitation? Part I: S2S Models

Abstract We analyze biases in subseasonal forecast models and their effect on Southwest United States (SWUS) precipitation prediction (2–6-week time scale). Cluster analyses identify three primary wave trains associated with SWUS precipitation: a meridional El Niño–Southern Oscillation (ENSO)–type wave train, an arching Pacific–North American (PNA)–type wave train, and a circumglobal zonal wave train. Compared to reanalysis, the models overrepresent the arching pattern, underrepresent the zonal pattern, and produce mixed results for the meridional pattern. The arching pattern overrepresentation is linked to model mean flow biases in the midlatitude–subpolar North Pacific, which cause a westward retraction of the region of forbidden linear Rossby wave propagation. The zonal pattern underrepresentation is linked to westerly biases in the subtropical jet, which cause a westward retraction of the waveguide in the midlatitude eastern North Pacific and divert wave trains southward. These results are confirmed using linear, barotropic ray-tracing analysis. In addition to mean state biases, the models also contain errors in their representation of the Madden–Julian oscillation (MJO). Tropical convection anomalies associated with the MJO are too weak and incoherent at lead times greater than 2 weeks when compared to reanalysis. Additionally, there is a strong SWUS precipitation signal as far out as 5 weeks after a strong MJO in reanalysis, associated with its persistent eastward propagation, but this signal is absent in the models. Our results indicate that there is still significant room for improvement in subseasonal predictions if we can reduce model biases in the background flow and improve the representation of the MJO.

Simulation of Pressure Waves During Deflagration Combustion of Clouds of Fuel-Air Mixtures

Simulation of Pressure Waves During Deflagration Combustion of Clouds of Fuel-Air Mixtures

The future of transcranial ultrasound as a precision brain interface

Our understanding of brain circuit operations and disorders has rapidly outpaced our ability to intervene and restore them. Developing technologies that can precisely interface with any brain region and circuit may combine diagnostics with therapeutic intervention, expediting personalised brain medicine. Transcranial ultrasound stimulation (TUS) is a promising noninvasive solution to this challenge, offering focal precision and scalability. By exploiting the biomechanics of pressure waves on brain tissue, TUS enables multi-site targeted neuromodulation across distributed circuits in the cortex and deeper areas alike. In this Essay, we explore the emergent evidence that TUS can functionally test and modify dysfunctional regions, effectively serving as a search and rescue tool for the brain. We define the challenges and opportunities faced by TUS as it moves towards greater target precision and integration with advanced brain monitoring and interventional technology. Finally, we propose a roadmap for the evolution of TUS as it progresses from a research tool to a clinically validated therapeutic for brain disorders.

Relationship between coronary atherosclerotic lesion and arterial stiffness in patients with coronary artery disease

Abstract Introduction Some of the previous studies demonstrated that arterial stiffness independently predicts mortality and morbidity associated with CAD. Purpose to evaluate the relationship between coronary atherosclerosis severity and arterial stiffness. Material and methods The study included 158 people aged 40 to 70 years: control group – 25 people (mean age 61,7±6,6 years; 21 men and 4 women) without cardiovascular diseases (CVD) and 133 patients (mean age 62,5±6,9 years; 80 men and 53 women) with CAD, confirmed by coronary angiography (CAG). Arterial stiffness was assessed using applanation tonometry (AT). Аssessment of the coronary calcium (CC) was performed with computer tomography (CT). Results In 133 patients with CAD, the results of AT were compared with the degree of atherosclerotic lesion according to CT and CAG data. All patients were divided into groups depending on the CC value. Group I included 19 people with a CC value of 0, group II - 55 people with a CC of up to 400, and group III - 59 patients with a CC of more than 400. With an increase in the degree of the atherosclerotic lesion, the values of peripheral and central pulse pressure (PP), augmentation index (AIx), additional augmentation index normalised for heart rate of 75 bpm (AIx@HR75) and pulse wave velocity (PWV) statistically significantly increased (Table 1). Indicators characterising augmentation of сentral PP and arterial stiffness also increased. Conclusion Increases in Pulse Pressure, Augmentation Index, and Pulse Wave Velocity reflect the worsening of atherosclerosis in coronary arteries, thereby indicating a higher risk of cardiovascular complications. Monitoring of these parameters can be crucial for early diagnosis and prevention of major adverse cardiovascular events.

Physiological disease pattern as assessed by PPGI in vessels with FFR and iFR discordance

Abstract Background Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) disagree on the hemodynamic significance of a coronary lesion in≈20% of cases. It is unclear whether the physiological pattern of disease is an influencing factor for this. This study assessed whether the physiological pattern of coronary artery disease (CAD) as assessed by angiography derived pullback pressure gradient index (PPGI) influences discordance between FFR and iFR measurement. Methods and results This study is a centralized off-line analysis by an independent academic core laboratory (CORRIB Core lab) of a prospective cohort of 444 vessels with both pressure wire-instantaneous wave free ratio (PW-iFR) and pressure wire-fractional flow reserve (PW-FFR) measurements. The study population consisted of a patients presenting with chronic coronary syndrome and having at least one epicardial coronary artery lesion with a 40% to 90% diameter stenosis by visual assessment on invasive coronary angiography. Three-hundred and ninety vessels (355 patients; mean age, 68±10 years; 70% men) with combined FFR, iFR, QFR and angiography derived PPGI were included. QFR was calculated using the QAngio XA 3D 2.1 software package (Medis Medical Imaging System BV, Leiden, The Netherlands). PPGI was calculated using the QFR 2.1.38.2 Research Edition software package. Cut points for hemodynamic significance were FFR ≤0.80 and iFR ≤0.89, respectively. Vessels were classified into FFR+/iFR+ (n=103; 26.4%), FFR-/iFR+ (n=27; 6.9%), FFR+/iFR- (n=38; 9.7%), and FFR-/iFR- (n=222; 57%) groups.. Median FFR, iFR, and QFR were 0.84 (0.77-0.90), 0.92 (0.88-0.97), and 0.83 (0.73-0.90) respectively. FFR disagreed with iFR in 16.7% (65 of 390). The Median PPGI was 0.75 (0.67-0.85). Vessels with PPGI ≥0.75 was considered to have predominantly focal disease pattern and vessels with PPGI &amp;lt;0.75 was considered to have predominantly diffuse disease pattern. The physiological pattern of disease was classified according to the angiography derived pullback pressure gradient index (PPGI) as predominantly physiologically focal (n=209; 53.6%) or predominantly physiologically diffuse (n=181; 46.4%). The median PPGI was significantly lower in FFR-/iFR+ vessels as compared to FFR+/iFR- vessels [0.65(0.60-0.69) vs 0.82(0.75-0.85), p&amp;lt;0.001). The physiological pattern of disease was the influencing factor relating to FFR/iFR discordance: predominantly physiologically focal was significantly associated with FFR+/iFR- (76.3% [29 of 38]), and predominantly physiologically diffuse was significantly associated with FFR-/iFR+ (96.3% [26 of 27]; P&amp;lt;0.001 for pattern of disease between FFR+/iFR- and FFR-/iFR+ groups). Conclusions The physiological pattern of coronary artery disease was an important influencing factor for FFR/iFR discordance.