scholarly journals Pressure Equilibrium Time of a Cyclic-Olefin Copolymer

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2309
Author(s):  
Benedikt Roth ◽  
Dietmar Drummer
Keyword(s):  
Dynamic Compression ◽  
Flow Behavior ◽  
Superposition Principle ◽  
Applied Pressure ◽  
Thermal Shrinkage ◽  
Compression Rate ◽  
Rate Dependency ◽  
Equilibrium Time ◽  
Simulation Techniques ◽  
Pressure Equilibrium

Integrative simulation techniques for predicting component properties, based on the conditions during processing, are becoming increasingly important. The calculation of orientations in injection molding, which, in addition to mechanical and optical properties, also affect the thermal shrinkage behavior, are modeled on the basis of measurements that cannot take into account the pressure driven flow processes, which cause the orientations during the holding pressure phase. Previous investigations with a high-pressure capillary rheometer (HPC) and closed counter pressure chamber (CPC) showed the significant effect of a dynamically applied pressure on the flow behavior, depending on the temperature and the underlying compression rate. At a constant compression rate, an effective pressure difference between the measuring chamber and the CPC was observed, which resulted in a stop of flow through the capillary referred to as dynamic compression induced solidification. In order to extend the material understanding to the moment after dynamic solidification, an equilibrium time, which is needed until the pressure signals equalize, was evaluated and investigated in terms of a pressure, temperature and a possible compression rate dependency in this study. The findings show an exponential increase of the determined equilibrium time as a function of the holding pressure level and a decrease of the equilibrium time with increasing temperature. In case of supercritical compression in the area of a dynamic solidification, a compression rate dependency of the determined equilibrium times is also found. The measurement results show a temperature-invariant behavior, which allows the derivation of a master curve, according to the superposition principle, to calculate the pressure equilibrium time as a function of the holding pressure and the temperature.

scholarly journals Pore-Scale Simulation of Particle Flooding for Enhancing Oil Recovery

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2305
Author(s):  
Xiangbin Liu ◽  
Le Wang ◽  
Jun Wang ◽  
Junwei Su
Keyword(s):  
Oil Recovery ◽  
Flow Behavior ◽  
Ct Scanning ◽  
Water Flooding ◽  
Pore Scale ◽  
Simulation Techniques ◽  
Three Phase ◽  
Remaining Oil ◽  
Three Phase Flow ◽  
Displacement Force

The particles, water and oil three-phase flow behaviors at the pore scale is significant to clarify the dynamic mechanism in the particle flooding process. In this work, a newly developed direct numerical simulation techniques, i.e., VOF-FDM-DEM method is employed to perform the simulation of several different particle flooding processes after water flooding, which are carried out with a porous structure obtained by CT scanning of a real rock. The study on the distribution of remaining oil and the displacement process of viscoelastic particles shows that the capillary barrier near the location with the abrupt change of pore radius is the main reason for the formation of remaining oil. There is a dynamic threshold in the process of producing remaining oil. Only when the displacement force exceeds this threshold, the remaining oil can be produced. The flow behavior of particle–oil–water under three different flooding modes, i.e., continuous injection, alternate injection and slug injection, is studied. It is found that the particle size and the injection mode have an important influence on the fluid flow. On this basis, the flow behavior, pressure characteristics and recovery efficiency of the three injection modes are compared. It is found that by injecting two kinds of fluids with different resistance increasing ability into the pores, they can enter into different pore channels, resulting in the imbalance of the force on the remaining oil interface and formation of different resistance between the channels, which can realize the rapid recovery of the remaining oil.

Drag Reducing Polymer in Helicoidal Flow

1981 ◽  
Vol 103 (4) ◽  
pp. 491-496 ◽  
Author(s):  
J. T. Kuo ◽  
L. S. G. Kovasznay
Keyword(s):  
Drag Reduction ◽  
Polymer Solution ◽  
Ph Value ◽  
Flow Behavior ◽  
Superposition Principle ◽  
Polymer Concentration ◽  
Second Phase ◽  
Additional Parameter ◽  
Solution Flow ◽  
Screw Pump

A novel flow configuration was explored for the study of the behavior of drag reducing polymers. A screw pump consisting of a smooth cylinder and a concentrically placed screw was used to create a strongly three-dimensional but essentially laminar flow. In the first phase of the study, the static pressure head developed by the screw pump was measured as a function of polymer concentration (polyox 10 to 100 ppm in water). A large increase of the developed head was observed that behaved in an analogous manner to drag reduction as far as concentration and straining of the polymer solution was concerned. In the second phase of the study, a new apparatus was constructed and the additional parameter of a superimposed through flow was included and the degree of failure of the superposition principle was established. Sensitivity of the phenomenon to chemicals like HCl, HNO3, and NaOH in the polymer solution was also studied. When the effect of these chemicals on the polymer solution flow behavior was presented in terms of the pH value of the polymer solution, it showed a similar trend to those observed in drag reduction.

Granular Flow Modeling and Simulation Using a Dynamic Finite Element Method

2007 ◽  
Author(s):  
M. A. Kabir ◽  
C. Fred Higgs ◽  
Michael R. Lovell
Keyword(s):  
Finite Element ◽  
Modeling And Simulation ◽  
Granular Flow ◽  
Flow Behavior ◽  
Food Service ◽  
Complex Nature ◽  
Complex Flow ◽  
Dual Nature ◽  
Simulation Techniques ◽  
Flow Phenomena

Granular flow behavior is of fundamental interest to the engineering and scientific community because of the prevalence of these flows in the pharmaceutical, agricultural, food service, and powder manufacturing industries. Granular materials exhibit very complex behavior, oftentimes acting as solids and at other times as fluids. This dual nature leads to very complex and rich behavior, which is not yet well understood. Therefore, the present investigation introduces a new technique that can potentially be used to unveil the mystery of granular flow phenomena. To this end, advanced finite element modeling and simulation techniques have been applied to the study of the complex nature of granular flow. More specifically, the explicit dynamic code LS-DYNA has been utilized to gain an understanding of the complex flow nature and collision stresses of granules in a shear cell.

A Three-Equation Eddy-Viscosity Model for Reynolds-Averaged Navier–Stokes Simulations of Transitional Flow

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
D. Keith Walters ◽  
Davor Cokljat
Keyword(s):  
Boundary Layer ◽  
Turbulent Flows ◽  
Eddy Viscosity ◽  
Flow Behavior ◽  
Applied Pressure ◽  
Plate Boundary ◽  
Low Frequency ◽  
Transitional Flow ◽  
Test Cases ◽  
Eddy Viscosity Model

An eddy-viscosity turbulence model employing three additional transport equations is presented and applied to a number of transitional flow test cases. The model is based on the k-ω framework and represents a substantial refinement to a transition-sensitive model that has been previously documented in the open literature. The third transport equation is included to predict the magnitude of low-frequency velocity fluctuations in the pretransitional boundary layer that have been identified as the precursors to transition. The closure of model terms is based on a phenomenological (i.e., physics-based) rather than a purely empirical approach and the rationale for the forms of these terms is discussed. The model has been implemented into a commercial computational fluid dynamics code and applied to a number of relevant test cases, including flat plate boundary layers with and without applied pressure gradients, as well as a variety of airfoil test cases with different geometries, Reynolds numbers, freestream turbulence conditions, and angles of attack. The test cases demonstrate the ability of the model to successfully reproduce transitional flow behavior with a reasonable degree of accuracy, particularly in comparison with commonly used models that exhibit no capability of predicting laminar-to-turbulent boundary layer development. While it is impossible to resolve all of the complex features of transitional and turbulent flows with a relatively simple Reynolds-averaged modeling approach, the results shown here demonstrate that the new model can provide a useful and practical tool for engineers addressing the simulation and prediction of transitional flow behavior in fluid systems.

Wind Energy Conversion: The Potential of a Novel Ducted Turbine for Residential and Commercial Applications

2013 ◽  
Author(s):  
N. Goudarzi ◽  
W. D. Zhu ◽  
H. Bahari
Keyword(s):  
Mathematical Model ◽  
Wind Power ◽  
Flow Behavior ◽  
Experimental Tests ◽  
Simulation Techniques ◽  
Ducted Turbine ◽  
Grid Applications ◽  
Commercial Applications ◽  
Four Quadrant ◽  
The Mathematical Model

A novel ducted turbine, referred to as a Wind Tower, for capturing wind power in either residential or commercial scale applications is studied theoretically and experimentally. A mathematical model is developed to predict the flow behavior inside the tower and a velocity coefficient is defined to correct the results at different test conditions. A wind tower prototype, including a four-quadrant-peak wind-catcher rooftop, a tower, a nozzle, and a turbine, is designed and fabricated. The captured wind power values from the mathematical model and the preliminary experimental tests are compared. While the mathematical model provides a good estimation of the output power in some cases, more precise experimental tests and simulation techniques are required to improve the mathematical model in some other cases. Significant changes in the output wind speed due to pressure differences created by the surrounding environment, the tower height, and the number of nozzles are observed. The advantages of being maintenance free, reliable, and sustainable, together with its special design that eliminates bird/bat mortality make the Wind Tower a promising solution for residential, commercial, and even off-grid applications.

scholarly journals A Hybrid Computational and Analytical Model of Inline Drip Emitters

2018 ◽  
Author(s):  
Jaya Narain ◽  
Amos G. Winter
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Flow Behavior ◽  
Applied Pressure ◽  
Computational Time ◽  
Matrix Formulation ◽  
Element Analysis ◽  
Line Load ◽  
Variable Resistor ◽  
Constant Flow Rate

This paper details a hybrid computational and analytical model to predict the performance of inline pressure-compensating (PC) drip irrigation emitters. The term inline refers to flow control devices mounted within the irrigation tubing. Pressure-compensating emitters deliver a relatively constant flow rate over a range applied pressure to accurately meter water to crops. Flow rate is controlled within the emitter by directing the water through a tortuous path (which imposes a fixed resistance), and then through a variable resistor composed of a flexible membrane that deflects under changes in pressure, restricting the flow path. An experimentally validated computational fluid dynamics (CFD) model was used to predict flow behavior through tortuous paths, and a pressure resistance parameter was derived to represent the pressure drop with a single variable. The bending and shearing mechanics of the membrane were modeled analytically and refined for accuracy by deriving a correction factor using finite element analysis. A least-squares matrix formulation that calculates the force applied by a line load of any shape, along which there is a prescribed deflection applied on a rectangular membrane, was derived and was found to be accurate to within one percent. The applicability of the assumption of locally fully developed flow through the pressure compensating chamber in a drip emitter was analyzed. The combined hybrid computational-analytical model reduces the computational time of modeling drip emitter performance from days to less than 30 minutes, dramatically lowering the time required to iterate and select optimal designs. The model was validated using three commercially available drip emitters, rated at 1.1, 2, and 3.8 L/hr. For each, the model predicted the flow rate with an error of twenty percent or less, as compared to the emitter performance published by the manufacturer.

Flow Behavior of Horinzontal Well Cmpleted within Two Sealing Fauts Inclined at Right Angle

2021 ◽  
Author(s):  
Johnson Johnson ◽  
Ezizanami Adewole
Keyword(s):  
Horizontal Well ◽  
Flow Behavior ◽  
Superposition Principle ◽  
External Boundary ◽  
Pressure Derivative ◽  
Effective Work ◽  
Drainage Radius ◽  
Dimensionless Pressure ◽  
Well Location ◽  
Wellbore Pressure

Abstract At inception of a production rate regime, a horizontal well is expected to sweep oil within its drainage radius until the flow transients are interrupted by an external boundary or an impermeable heterogeneity. If the interruption is an impermeable heterogeneity or sealing fault, then the architecture of the heterogeneity must be deciphered in order to be able to design and implement an effective work-over or well re-entry to boost oil production from the reservoir. In this paper, therefore, the behavior of a horizontal well located within a pair of sealing faults inclined at 90 degrees is investigated using flow pressures and their derivatives. It is assumed that the well flow pressure is undergoing infinite activity, and each fault acts as a plane mirror. The total pressure drop in the object well is calculated by superposition principle. Damage and mechanical skin and wellbore storage are not considered. The main objective of our investigation is to establish identifiable signatures on pressure-time plots that represent infinite flow in the presence of adjacent no flow faults inclined at 90degrees. Results obtained show that the flowing wellbore pressure is influenced strongly by object well design, object well distance from each fault, and distance of each image from the object well. Irrespective of object well distance from the fault, there are three (3) images formed. Central object well location yields a square polygon, with two image wells nearer to the object well at equidistance from the object well, and the farthest image well to be 2d2. From the object well For off-centered object well location within the faults, a rectangular polygon is formed, with each image at a different distance from one well to another. Dimensionless pressure and dimensionless pressure derivative gradients during infinite-acting flow are (4.6052/LD) and 2/LD, respectively for all well locations within the faults.

Investigations Into the Flow Behavior in a Nonparallel Shrouded Diffuser of a Centrifugal Fan for Augmented Performance

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
N. Madhwesh ◽  
K. Vasudeva Karanth ◽  
N. Yagnesh Sharma
Keyword(s):  
Numerical Analysis ◽  
Static Pressure ◽  
Numerical Study ◽  
Flow Behavior ◽  
Pressure Rise ◽  
Radial Pressure ◽  
Vital Role ◽  
Centrifugal Fan ◽  
Energy Transformation ◽  
Pressure Equilibrium

It is a well-known fact that the diffuser of a centrifugal fan plays a vital role in the energy transformation leading to better static pressure rise and efficiency. Many researchers have worked on modified geometry with respect to both impeller and diffuser so as to extract better efficiency of the fan. This paper highlights a unique numerical study on the performance of a centrifugal fan, which has a diffuser having nonparallel shrouds. The shroud geometry is parametrically varied by adopting various convergence ratios (CR) for the nonparallel shrouds encompassing the diffuser passage. It is revealed in the study that there exists an optimal CR for which the performance is improved over the regular parallel shrouded diffuser passage (base model). It is observed from the numerical analysis that for a nonparallel convergent shroud corresponding to a CR of 0.35, a relatively higher head coefficient of 3.6% is obtained when compared to that of the base model. This configuration also yields a higher theoretical efficiency of about 2.1% corroborating the improvement in head coefficient. This study predicts a design prescription for nonparallel diffuser shrouds of a centrifugal fan for augmented performance due to the fact that the converging region accelerates and guides the flow efficiently by establishing radial pressure equilibrium.

scholarly journals Dynamic Compression Induced Solidification

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 488
Author(s):  
Benedikt Roth ◽  
Wolfgang Wildner ◽  
Dietmar Drummer
Keyword(s):  
Measurement Errors ◽  
Dynamic Compression ◽  
Dynamic Pressure ◽  
Linear Increase ◽  
Compression Rate ◽  
Aspect Ratios ◽  
Flow Through ◽  
Static Conditions ◽  
Solidification Pressure

This study presents a method for the determination of the dynamic pressure-dependent solidification of polycarbonate (PC) during flow using high pressure capillary rheometer (HPC) measurements. In addition, the pressure-dependent solidification was determined by isothermal pressure-volume-temperature (pvT) measurements under static conditions without shear. Independent of the compression velocity, a linear increase of the solidification pressure with temperature could be determined. Furthermore, the results indicate that the relaxation time at a constant temperature and compression rate can increase to such an extent that the material can no longer follow within the time scale specified by the compression rate. Consequently, the flow through the capillary stops at a specific pressure, with higher compression rates resulting in lower solidification pressures. Consequently, in regard to HPC measurements, it could be shown that the evaluation of the pressure via a pressure hole can lead to measurement errors in the limit range. Since the filling process in injection molding usually takes place under such transient conditions, the results are likely to be relevant for modelling the flow processes of thin-walled and microstructures with high aspect ratios.

Calibration of Hyperelastic Material Properties of the Human Lumbar Intervertebral Disc under Fast Dynamic Compressive Loads

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Eric Wagnac ◽  
Pierre-Jean Arnoux ◽  
Anaïs Garo ◽  
Marwan El-Rich ◽  
Carl-Eric Aubin
Keyword(s):  
Material Properties ◽  
Dynamic Compression ◽  
Fracture Pattern ◽  
Experimental Results ◽  
Hyperelastic Material ◽  
Rate Dependency ◽  
Material Constants ◽  
Compressive Stiffness ◽  
Load Rate ◽  
Fast Dynamic

Under fast dynamic loading conditions (e.g. high-energy impact), the load rate dependency of the intervertebral disc (IVD) material properties may play a crucial role in the biomechanics of spinal trauma. However, most finite element models (FEM) of dynamic spinal trauma uses material properties derived from quasi-static experiments, thus neglecting this load rate dependency. The aim of this study was to identify hyperelastic material properties that ensure a more biofidelic simulation of the IVD under a fast dynamic compressive load. A hyperelastic material law based on a first-order Mooney-Rivlin formulation was implemented in a detailed FEM of a L2-L3 functional spinal unit (FSU) to represent the mechanical behavior of the IVD. Bony structures were modeled using an elasto-plastic Johnson-Cook material law that simulates bone fracture while ligaments were governed by a viscoelastic material law. To mimic experimental studies performed in fast dynamic compression, a compressive loading velocity of 1 m/s was applied to the superior half of L2, while the inferior half of L3 was fixed. An exploratory technique was used to simulate dynamic compression of the FSU using 34 sets of hyperelastic material constants randomly selected using an optimal Latin hypercube algorithm and a set of material constants derived from quasi-static experiments. Selection or rejection of the sets of material constants was based on compressive stiffness and failure parameters criteria measured experimentally. The two simulations performed with calibrated hyperelastic constants resulted in nonlinear load-displacement curves with compressive stiffness (7335 and 7079 N/mm), load (12,488 and 12,473 N), displacement (1.95 and 2.09 mm) and energy at failure (13.5 and 14.7 J) in agreement with experimental results (6551 ± 2017 N/mm, 12,411 ± 829 N, 2.1 ± 0.2 mm and 13.0 ± 1.5 J respectively). The fracture pattern and location also agreed with experimental results. The simulation performed with constants derived from quasi-static experiments showed a failure energy (13.2 J) and a fracture pattern and location in agreement with experimental results, but a compressive stiffness (1580 N/mm), a failure load (5976 N) and a displacement to failure (4.8 mm) outside the experimental corridors. The proposed method offers an innovative way to calibrate the hyperelastic material properties of the IVD and to offer a more realistic simulation of the FSU in fast dynamic compression.

Sign in / Sign up

Export Citation Format

Share Document