scholarly journals A Model for the Simulation of the CnEm Nonionic Surfactant Family Derived from Recent Experimental Results

2020 ◽  
Author(s):  
Michael Johnston ◽  
Andrew Duff ◽  
Richard L. Anderson ◽  
William Swope
Keyword(s):  
Experimental Data ◽  
Computational Models ◽  
Nonionic Surfactants ◽  
Dissipative Particle Dynamics ◽  
Coarse Graining ◽  
Experimental Results ◽  
Important Class ◽  
Moderate Amount ◽  
Weighted Averages ◽  
Aggregation Numbers

<div><div><div><p>Using a comprehensive set of recently published experimental results for training and validation, we have developed computational models appropriate for simulations of aqueous solutions of poly(ethylene oxide) alkyl ethers, an important class of micelle- forming nonionic surfactants, usually denoted CnEm. These models are suitable for use in simulations that employ a moderate amount of coarse graining and especially for dissipative particle dynamics (DPD), which we adopt in this work.</p><p><br></p><p>The experimental data used for training and validation were reported earlier and produced in our laboratory using dynamic light scattering (DLS) measurements per- formed on twelve members of the CnEm compound family yielding micelle size dis- tribution functions and mass weighted mean aggregation numbers at each of several surfactant concentrations. The range of compounds and quality of the experimental results were designed to support the development of computational models. An es- sential feature of this work is that all simulation results were analysed in a way that is consistent with the experimental data. Proper account is taken of the fact that a broad distribution of micelle sizes exists, so mass weighted averages (rather than num- ber weighted averages) over this distribution are required for the proper comparison of simulation and experimental results.</p><p><br></p><p>The resulting DPD force field reproduces several important trends seen in the exper- imental critical micelle concentrations and mass averaged mean aggregation numbers with respect to surfactant characteristics and concentration. We feel it can be used to investigate a number of open questions regarding micelle sizes and shapes and their dependence on surfactant concentration for this important class of nonionic surfactants.</p></div></div></div>

scholarly journals A Model for the Simulation of the CnEm Nonionic Surfactant Family Derived from Recent Experimental Results

2020 ◽  
Author(s):  
Michael Johnston ◽  
Andrew Duff ◽  
Richard L. Anderson ◽  
William Swope
Keyword(s):  
Experimental Data ◽  
Computational Models ◽  
Nonionic Surfactants ◽  
Dissipative Particle Dynamics ◽  
Coarse Graining ◽  
Experimental Results ◽  
Important Class ◽  
Moderate Amount ◽  
Weighted Averages ◽  
Aggregation Numbers

<div><div><div><p>Using a comprehensive set of recently published experimental results for training and validation, we have developed computational models appropriate for simulations of aqueous solutions of poly(ethylene oxide) alkyl ethers, an important class of micelle- forming nonionic surfactants, usually denoted CnEm. These models are suitable for use in simulations that employ a moderate amount of coarse graining and especially for dissipative particle dynamics (DPD), which we adopt in this work.</p><p><br></p><p>The experimental data used for training and validation were reported earlier and produced in our laboratory using dynamic light scattering (DLS) measurements per- formed on twelve members of the CnEm compound family yielding micelle size dis- tribution functions and mass weighted mean aggregation numbers at each of several surfactant concentrations. The range of compounds and quality of the experimental results were designed to support the development of computational models. An es- sential feature of this work is that all simulation results were analysed in a way that is consistent with the experimental data. Proper account is taken of the fact that a broad distribution of micelle sizes exists, so mass weighted averages (rather than num- ber weighted averages) over this distribution are required for the proper comparison of simulation and experimental results.</p><p><br></p><p>The resulting DPD force field reproduces several important trends seen in the exper- imental critical micelle concentrations and mass averaged mean aggregation numbers with respect to surfactant characteristics and concentration. We feel it can be used to investigate a number of open questions regarding micelle sizes and shapes and their dependence on surfactant concentration for this important class of nonionic surfactants.</p></div></div></div>

scholarly journals Renormalization group theory of molecular dynamics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daiji Ichishima ◽  
Yuya Matsumura
Keyword(s):  
Molecular Dynamics ◽  
Renormalization Group ◽  
Critical Exponent ◽  
Computational Efficiency ◽  
Large Scale ◽  
Dissipative Particle Dynamics ◽  
Computational Cost ◽  
Coarse Graining ◽  
Spatial Dimension ◽  
Deborah Number

AbstractLarge scale computation by molecular dynamics (MD) method is often challenging or even impractical due to its computational cost, in spite of its wide applications in a variety of fields. Although the recent advancement in parallel computing and introduction of coarse-graining methods have enabled large scale calculations, macroscopic analyses are still not realizable. Here, we present renormalized molecular dynamics (RMD), a renormalization group of MD in thermal equilibrium derived by using the Migdal–Kadanoff approximation. The RMD method improves the computational efficiency drastically while retaining the advantage of MD. The computational efficiency is improved by a factor of $$2^{n(D+1)}$$ 2 n ( D + 1 ) over conventional MD where D is the spatial dimension and n is the number of applied renormalization transforms. We verify RMD by conducting two simulations; melting of an aluminum slab and collision of aluminum spheres. Both problems show that the expectation values of physical quantities are in good agreement after the renormalization, whereas the consumption time is reduced as expected. To observe behavior of RMD near the critical point, the critical exponent of the Lennard-Jones potential is extracted by calculating specific heat on the mesoscale. The critical exponent is obtained as $$\nu =0.63\pm 0.01$$ ν = 0.63 ± 0.01 . In addition, the renormalization group of dissipative particle dynamics (DPD) is derived. Renormalized DPD is equivalent to RMD in isothermal systems under the condition such that Deborah number $$De\ll 1$$ D e ≪ 1 .

Convective Losses From Cavity Solar Receivers—Comparisons Between Analytical Predictions and Experimental Results

1983 ◽  
Vol 105 (1) ◽  
pp. 29-33 ◽  
Author(s):  
A. M. Clausing
Keyword(s):  
Experimental Data ◽  
Experimental Evidence ◽  
Analytical Model ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Simple Analytical Model ◽  
Refined Model ◽  
Wall Area

Cavity solar receivers are generally believed to have higher thermal efficiencies than external receivers due to reduced losses. A simple analytical model was presented by the author which indicated that the ability to heat the air inside the cavity often controls the convective loss from cavity receivers. Thus, if the receiver contains a large amount of inactive hot wall area, it can experience a large convective loss. Excellent experimental data from a variety of cavity configurations and orientations have recently become available. These data provided a means of testing and refining the analytical model. In this manuscript, a brief description of the refined model is presented. Emphasis is placed on using available experimental evidence to substantiate the hypothesized mechanisms and assumptions. Detailed comparisons are given between analytical predictions and experimental results. Excellent agreement is obtained, and the important mechanisms are more clearly delineated.

A Technique for the Laboratory Determination of Recirculation in Single Needle Dialysis

1993 ◽  
Vol 16 (2) ◽  
pp. 63-70 ◽  
Author(s):  
N.A. Hoenich ◽  
P.T. Smirthwaite ◽  
C. Woffindin ◽  
P. Lancaster ◽  
T.H. Frost ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Experimental Results ◽  
New Technique ◽  
Treatment Efficiency ◽  
Single Lumen ◽  
Theoretical Predictions ◽  
Lumen Catheter ◽  
A New Technique

Recirculation is an important factor in single needle dialysis and, if high, can compromise treatment efficiency. To provide information regarding recirculation characteristics of access devices used in single needle dialysis, we have developed a new technique to characterise recirculation and have used this to measure the recirculation of a Terumo 15G fistula needle and a VasCath SC2300 single lumen catheter. The experimentally obtained results agreed well with those established clinically (8.5 ± 2.4% and 18.4 ± 3.4%). The experimental results have also demonstrated a dependence on access type, pump speeds and fistula flow rate. A comparison of experimental data with theoretical predictions showed that the latter exceeded those measured with the largest contribution being due to the experimental fistula.

Validating Numerical CFD Simulations With Experimental Data for Turbulence Phenomena in Axial Flow Gas Turbine Diffusers

2009 ◽  
Author(s):  
Farrokh Zarifi-Rad ◽  
Hamid Vajihollahi ◽  
James O’Brien
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Axial Flow ◽  
Experimental Results ◽  
Scale Model ◽  
Data Set ◽  
Pressure Profiles ◽  
Scale Models ◽  
Inlet Conditions

Scale models give engineers an excellent understanding of the aerodynamic behavior behind their design; nevertheless, scale models are time consuming and expensive. Therefore computer simulations such as Computational Fluid Dynamics (CFD) are an excellent alternative to scale models. One must ask the question, how close are the CFD results to the actual fluid behavior of the scale model? In order to answer this question the engineering team investigated the performance of a large industrial Gas Turbine (GT) exhaust diffuser scale model with performance predicted by commercially available CFD software. The experimental results were obtained from a 1:12 scale model of a GT exhaust diffuser with a fixed row of blades to simulate the swirl generated by the last row of turbine blades five blade configurations. This work is to validate the effect of the turbulent inlet conditions on an axial diffuser, both on the experimental front and on the numerical analysis approach. The object of this work is to bring forward a better understanding of velocity and static pressure profiles along the gas turbine diffusers and to provide an accurate experimental data set to validate the CFD prediction. For the CFD aspect, ANSYS CFX software was chosen as the solver. Two different types of mesh (hexagonal and tetrahedral) will be compared to the experimental results. It is understood that hexagonal (HEX) meshes are more time consuming and more computationally demanding, they are less prone to mesh sensitivity and have the tendancy to converge at a faster rate than the tetrahedral (TET) mesh. It was found that the HEX mesh was able to generate more consistent results and had less error than TET mesh.

THE SIMULATION OF POLYSTYRENE/NANOPARTICLES COMPOSITE MICROSPHERES USING DISSIPATIVE PARTICLE DYNAMICS

2013 ◽  
Vol 12 (02) ◽  
pp. 1250111 ◽  
Author(s):  
HAILONG XU ◽  
QIUYU ZHANG ◽  
HEPENG ZHANG ◽  
BAOLIANG ZHANG ◽  
CHANGJIE YIN
Keyword(s):  
Dissipative Particle Dynamics ◽  
Sodium Dodecyl ◽  
Coarse Graining ◽  
Particle Dynamics ◽  
Coarse Grained ◽  
Polystyrene Nanoparticles ◽  
Coarse Grained Model ◽  
Composite Microspheres ◽  
Polystyrene Matrix ◽  
Materials Studio

Dissipative particle dynamics (DPD) was initially used to simulate the polystyrene/nanoparticle composite microspheres (PNCM) in this paper. The coarse graining model of PNCM was established. And the DPD parameterization of the model was represented in detail. The DPD repulsion parameters were calculated from the cohesive energy density which could be calculated by amorphous modules in Materials Studio. The equilibrium configuration of the simulated PNCM shows that the nanoparticles were actually "modified" with oleic acid and the modified nanoparticles were embedded in the bulk of polystyrene. As sodium dodecyl sulfate (SDS) was located in the interface between water and polystyrene, the hydrophilic head of SDS stretched into water while the hydrophobic tailed into polystyrene. All simulated phenomena were consistent with the experimental results in preparation of polystyrene/nanoparticles composite microspheres. The effect of surface modification of nanoparticles on its dispersion in polystyrene matrix was also studied by adjusting the interaction parameters between the OA and NP beads. The final results indicated that the nanoparticles removed from the core of composite microsphere to the surface with increase of a OA-NP . All the simulated results demonstrated that our coarse–grained model was reasonable.

Coarse-Graining of Chain Models in Dissipative Particle Dynamics Simulations†

2011 ◽  
Vol 50 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Justin R. Spaeth ◽  
Todd Dale ◽  
Ioannis G. Kevrekidis ◽  
Athanassios Z. Panagiotopoulos
Keyword(s):  
Dissipative Particle Dynamics ◽  
Coarse Graining ◽  
Particle Dynamics ◽  
Dynamics Simulations

Heats of mixing of binary mixtures of pyridine base with n-alkane

1988 ◽  
Vol 66 (7) ◽  
pp. 1625-1627 ◽  
Author(s):  
Teresa Kasprzycka-Guttman ◽  
Juan H. Vera
Keyword(s):  
Experimental Data ◽  
Binary Mixtures ◽  
Experimental Results ◽  
Pyridine Base ◽  
Heats Of Mixing

Heats of mixing of 2,4-lutidine and 2,4,6-collidine with n-alkanes were measured at 293.15 K using an isothermal dilution calorimeter. Experimental results were fitted with a Redlich–Kister polynomial. Experimental data and coefficients for the Redlich–Kister polynomials are reported.

A Statistical Adaptable Distribution Function Model for Low Probabilities of Failure

1993 ◽  
Author(s):  
Suryaji R. Bhonsle ◽  
Paul Thompson
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Experimental Results ◽  
Function Model ◽  
Log Normal ◽  
Function Models

Abstract Weibull, log normal, and some other Distribution function models (D.F.M.) have a tendency to deviate from experimental results. This deviation, either exceedingly conservative or nonconservative, is amplified at low probabilities of failure. To remedy such problems a new D.F.M. is derived. It is then used to predict low probabilities of failure. The predictions are consistent with experimental data and are not too conservative or too nonconservative.

Lherzolite - carbonatite melt interaction in the presence of additive CO2 and H2O: Experimental data at 5.5 GPa and 1200-1450°C

2021 ◽  
Author(s):  
Aleksei Kruk ◽  
Alexander Sokol
Keyword(s):  
Experimental Data ◽  
Lithospheric Mantle ◽  
Fluid Phase ◽  
Experimental Results ◽  
Silicate Melt ◽  
Silicate Melts ◽  
Garnet Lherzolite ◽  
Russian Science ◽  
Continental Lithospheric Mantle

&lt;p&gt;We study the reaction of garnet lherzolite with carbonatitic melt rich in molecular CO&lt;sub&gt;2&lt;/sub&gt; and/or H&lt;sub&gt;2&lt;/sub&gt;O in experiments at 5.5 GPa and 1200-1450&amp;#176;C. The experimental results show that carbonation of olivine with formation of orthopyroxene and magnesite can buffer the CO&lt;sub&gt;2&lt;/sub&gt; contents in the melt, which impedes immediate separation of CO&lt;sub&gt;2&lt;/sub&gt; fluid from melt equilibrated with the peridotite source. The solubility of molecular CO&lt;sub&gt;2&lt;/sub&gt; in melt decreases from 20-25 wt.% at 4.5-6.8 wt.% SiO&lt;sub&gt;2&lt;/sub&gt; typical of carbonatite to 7-12 wt.% in more silicic kimberlite-like melts with 26-32 wt.% SiO&lt;sub&gt;2&lt;/sub&gt;. Interaction of garnet lherzolite with carbonatitic melt (2:1) in the presence of 2-3 wt.% H&lt;sub&gt;2&lt;/sub&gt;O and 9-13 wt.% molecular CO&lt;sub&gt;2&lt;/sub&gt; at 1200-1450&amp;#176;&amp;#1057; yields low SiO&lt;sub&gt;2&lt;/sub&gt; (&lt;10 wt.%) alkali&amp;#8208;carbonatite melts, which shows multiphase saturation with magnesite-bearing garnet harzburgite. Thus, carbonatitic melts rich in volatiles can originate in a harzburgite source at moderate temperatures common to continental lithospheric mantle (CLM).&lt;/p&gt;&lt;p&gt;Having separated from the source, carbonatitic magma enriched in molecular CO&lt;sub&gt;2&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O can rapidly acquire a kimberlitic composition with &gt;25 wt.% SiO&lt;sub&gt;2 &lt;/sub&gt;by dissolution and carbonation of entrapped peridotite. Furthermore, interaction of garnet lherzolite with carbonatitic melt rich in K, CO&lt;sub&gt;2&lt;/sub&gt;, and H&lt;sub&gt;2&lt;/sub&gt;O at 1350&amp;#176;&amp;#1057; produces immiscible kimberlite-like carbonate-silicate and K-rich silicate melts. Quenched silicate melt develops lamelli of foam-like vesicular glass. Differentiation of immiscible melts early during ascent may equalize the compositions of kimberlite magmas generated in different CLM sources. The fluid phase can release explosively from ascending magma at lower pressures as a result of SiO&lt;sub&gt;2&lt;/sub&gt; increase which reduces the solubility of CO&lt;sub&gt;2&lt;/sub&gt; due to decarbonation reaction of magnesite and orthopyroxene.&lt;/p&gt;&lt;p&gt;The research was performed by a grant of the Russian Science Foundation (19-77-10023).&lt;/p&gt;

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