This article provided a research for the trend of heat transfer and flow field through a 2-dimensional wavy duct. To construct a grid mesh, the physical domain was transferred to the computational domain and finite volume scheme was used for discretizing the governing equations. Through the simulation, the flow regime stayed in laminar mode. Constant temperature boundary condition has been used for solid walls. Air was used as a working fluid. Existence of waves makes some phenomenon like flow separation. Effect of Reynolds number, wave width, and wave number has been analyzed and velocity distribution, heat transfer coefficient, and tangential stress were computed for different cases. The final results were compared with the same straight duct. The entropy generation minimization method has been used for better comparison between final results.

Ouldouz Nourani Zonouz

Mehdi Salmanpour

Numerical Analysis of Flow Field and Heat Transfer of 2D Wavy Ducts and Optimization by Entropy Generation Minimization Method

The accretion of relativistic and nonrelativistic fluids into a Reissner-Nordstr&#246;m black hole is revisited. The position of the critical point, the flow velocity at this point, and the accretion rate are only slightly affected with respect to the Schwarzschild case when the fluid is nonrelativistic. On the contrary, relativistic fluids cross the critical point always subsonically. In this case, the sonic point is located near the event horizon, which is crossed by the fluid with a velocity less than the light speed. The accretion rate of relativistic fluids by a Reissner-Nordstr&#246;m black hole is reduced with respect to those estimated for uncharged black holes, being about 60&#37; less for the extreme case (charge-to-mass ratio equal to one).

J. A. de Freitas Pacheco

Relativistic Accretion into a Reissner-Nordstr&#246;m Black Hole Revisited

A water desorption process of a mixture of room temperature ionic liquid (<i>N</i>, <i>N</i>-diethyl-<i>N</i>-methyl-<i>N</i>-(2-methoxyethyl) ammonium tetrafluoroborate) and water was investigated via simultaneous X-ray diffraction and differential scanning calorimetry (DSC) measurements, in which relative humidity was controlled by a water vapor generator. In these measurements, <svg style="vertical-align:-3.13504pt;width:28.7875px;" id="M2" height="14.6" version="1.1" viewBox="0 0 28.7875 14.6" width="28.7875" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(1.25,0,0,-1.25,0,14.6)"><g transform="translate(72,-60.32)"><text transform="matrix(1,0,0,-1,-71.95,63.5)"><tspan style="font-size: 12.50px; " x="0" y="0">H</tspan></text><text transform="matrix(1,0,0,-1,-62.92,60.37)"><tspan style="font-size: 8.75px; " x="0" y="0">2</tspan></text><text transform="matrix(1,0,0,-1,-58.05,63.5)"><tspan style="font-size: 12.50px; " x="0" y="0">O</tspan></text></g></g></svg> concentration was estimated by the peak position of the <i>principal</i> peak in X-ray diffraction patterns, and the thermal property associated with a mixing state was detected by a DSC thermograph. In addition, the density of the mixture was measured as a macroscopic property. <i>In situ</i> observations revealed that the thermally unstable mixing state in the water-rich region has an important correlation with density and thermal and structural properties.

Hiroshi Abe

Tomohiro Mori

Yusuke Imai

Yukihiro Yoshimura

Water Desorption Process in Room Temperature Ionic Liquid-<svg style="vertical-align:-3.27605pt" height="15.5125" version="1.1" viewBox="0 0 32.412498 15.5125" width="32.412498" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,11.363)"><path id="x48" d="M729 650v-28q-62 -5 -76 -19.5t-14 -75.5v-404q0 -62 13.5 -76t75.5 -19v-28h-268v28q65 5 79.5 19t14.5 76v199h-341v-199q0 -62 14 -76t76 -19v-28h-263v28q61 5 74.5 19t13.5 76v404q0 62 -14 76t-76 19v28h259v-28q-58 -5 -71 -19t-13 -76v-162h341v162&#xA;q0 61 -13.5 75.5t-72.5 19.5v28h261z" /></g><g transform="matrix(.012,-0,0,-.012,13.087,15.45)"><path id="x1D7D0" d="M453 211h25l-46 -211h-415v23q97 102 151 166q42 49 81 110q51 78 51 148q0 56 -31.5 91.5t-87.5 35.5q-77 0 -122 -90h-28q67 204 223 204q82 0 132 -49.5t50 -133.5q0 -110 -114 -218l-162 -154h140q82 0 107 13q27 13 46 65z" /></g><g transform="matrix(.017,-0,0,-.017,19.65,11.363)"><path id="x4F" d="M381 665q131 0 226.5 -93t95.5 -239q0 -158 -96 -253t-238 -95q-137 0 -231 95t-94 238q0 142 92.5 244.5t244.5 102.5zM359 629q-89 0 -151 -74.5t-62 -208.5q0 -141 69 -233t175 -92q90 0 150.5 74t60.5 211q0 152 -69 237.5t-173 85.5z" /></g></svg> Mixtures: <italic>N</italic>, <italic>N</italic>-diethyl-<italic>N</italic>-methyl-<italic>N</italic>-(2-methoxyethyl) Ammonium Tetrafluoroborate

By a simple differential thermal analysis (DTA) system, the concentration dependence of the glass transition temperatures (<svg style="vertical-align:-4.77652pt;width:15.1625px;" id="M1" height="16.2875" version="1.1" viewBox="0 0 15.1625 16.2875" width="15.1625"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,16.2875)">
		<g transform="translate(72,-58.97)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑇</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.07,60.66)">
				<tspan style="font-size: 8.75px; " x="0" y="0">𝑔</tspan>
			</text>

		</g>
	</g>
</svg>s) for the quaternary ammonium-type ionic liquid, <i  >N</i>,<i  >N</i>-diethyl-<i  >N</i>-methyl-<i  >N</i>-(2-methoxyethyl)ammonium bromide [DEME][Br] and H<sub  >2</sub>O mixtures, after quick precooling was measured as a function of water concentration <svg style="vertical-align:-0.11285pt;width:8.7250004px;" id="M2" height="7.1624999" version="1.1" viewBox="0 0 8.7250004 7.1624999" width="8.7250004"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,7.1625)">
		<g transform="translate(72,-66.27)">
			<text transform="matrix(1,0,0,-1,-71.95,66.44)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑥</tspan>
			</text>

		</g>
	</g>
</svg> (mol&#x25; H2O). We compared the results with the previous results of [DEME][I]-H<sub  >2</sub>O and [DEME][BF<sub  >4</sub>]-H<sub  >2</sub>O mixtures in which a double-glass transition behavior was observed. Remarkably, the [DEME][Br]-H<sub  >2</sub>O mixtures basically show one-<svg style="vertical-align:-4.77652pt;width:15.1625px;" id="M3" height="16.2875" version="1.1" viewBox="0 0 15.1625 16.2875" width="15.1625"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,16.2875)">
		<g transform="translate(72,-58.97)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑇</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.07,60.66)">
				<tspan style="font-size: 8.75px; " x="0" y="0">𝑔</tspan>
			</text>

		</g>
	</g>
</svg> behavior and the <svg style="vertical-align:-4.77652pt;width:15.1625px;" id="M4" height="16.2875" version="1.1" viewBox="0 0 15.1625 16.2875" width="15.1625"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,16.2875)">
		<g transform="translate(72,-58.97)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑇</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.07,60.66)">
				<tspan style="font-size: 8.75px; " x="0" y="0">𝑔</tspan>
			</text>

		</g>
	</g>
</svg> decreases monotonically with increasing H<sub  >2</sub>O content up to around <svg style="vertical-align:-0.27588pt;width:55.462502px;" id="M5" height="11.225" version="1.1" viewBox="0 0 55.462502 11.225" width="55.462502"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,11.225)">
		<g transform="translate(72,-63.02)">
			<text transform="matrix(1,0,0,-1,-71.95,63.35)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑥</tspan>
				<tspan style="font-size: 12.50px; " x="10.339981" y="0">=</tspan>
				<tspan style="font-size: 12.50px; " x="22.380369" y="0">9</tspan>
				<tspan style="font-size: 12.50px; " x="28.63187" y="0">1</tspan>
				<tspan style="font-size: 12.50px; " x="34.883369" y="0">.</tspan>
				<tspan style="font-size: 12.50px; " x="38.009121" y="0">5</tspan>
			</text>

		</g>
	</g>
</svg>. But it suddenly jumps to higher <svg style="vertical-align:-4.77652pt;width:15.1625px;" id="M6" height="16.2875" version="1.1" viewBox="0 0 15.1625 16.2875" width="15.1625"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,16.2875)">
		<g transform="translate(72,-58.97)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑇</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.07,60.66)">
				<tspan style="font-size: 8.75px; " x="0" y="0">𝑔</tspan>
			</text>

		</g>
	</g>
</svg> value at a specific <svg style="vertical-align:-0.27588pt;width:54.4375px;" id="M7" height="11.0375" version="1.1" viewBox="0 0 54.4375 11.0375" width="54.4375"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,11.0375)">
		<g transform="translate(72,-63.17)">
			<text transform="matrix(1,0,0,-1,-71.95,63.5)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑥</tspan>
				<tspan style="font-size: 12.50px; " x="10.339981" y="0">=</tspan>
				<tspan style="font-size: 12.50px; " x="18.904535" y="0">∼</tspan>
				<tspan style="font-size: 12.50px; " x="30.944925" y="0">9</tspan>
				<tspan style="font-size: 12.50px; " x="37.196426" y="0">2</tspan>
			</text>

		</g>
	</g>
</svg>. At this very limited point, two <svg style="vertical-align:-4.77652pt;width:15.1625px;" id="M8" height="16.2875" version="1.1" viewBox="0 0 15.1625 16.2875" width="15.1625"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,16.2875)">
		<g transform="translate(72,-58.97)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑇</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.07,60.66)">
				<tspan style="font-size: 8.75px; " x="0" y="0">𝑔</tspan>
			</text>

		</g>
	</g>
</svg>s (<svg style="vertical-align:-4.77652pt;width:46.775002px;" id="M9" height="16.2875" version="1.1" viewBox="0 0 46.775002 16.2875" width="46.775002"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,16.2875)">
		<g transform="translate(72,-58.97)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑇</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.07,60.66)">
				<tspan style="font-size: 8.75px; " x="0" y="0">𝑔</tspan>
				<tspan style="font-size: 8.75px; " x="4.305984" y="0">1</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-55.89,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">,</tspan>
				<tspan style="font-size: 12.50px; " x="5.2012482" y="0">𝑇</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-43.81,60.66)">
				<tspan style="font-size: 8.75px; " x="0" y="0">𝑔</tspan>
				<tspan style="font-size: 8.75px; " x="4.305984" y="0">2</tspan>
			</text>

		</g>
	</g>
</svg>) which we might consider as a transition state from the structure belonging to the <svg style="vertical-align:-4.77652pt;width:20.200001px;" id="M10" height="16.2875" version="1.1" viewBox="0 0 20.200001 16.2875" width="20.200001"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,16.2875)">
		<g transform="translate(72,-58.97)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑇</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.07,60.66)">
				<tspan style="font-size: 8.75px; " x="0" y="0">𝑔</tspan>
				<tspan style="font-size: 8.75px; " x="4.305984" y="0">1</tspan>
			</text>

		</g>
	</g>
</svg> group to another one due to the <svg style="vertical-align:-4.77652pt;width:20.200001px;" id="M11" height="16.2875" version="1.1" viewBox="0 0 20.200001 16.2875" width="20.200001"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,16.2875)">
		<g transform="translate(72,-58.97)">
			<text transform="matrix(1,0,0,-1,-71.95,63.79)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑇</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-65.07,60.66)">
				<tspan style="font-size: 8.75px; " x="0" y="0">𝑔</tspan>
				<tspan style="font-size: 8.75px; " x="4.305984" y="0">2</tspan>
			</text>

		</g>
	</g>
</svg> group were observed. These results clearly reflect the difference in the anionic effects among Br<sup  >&#x2212;</sup>, I<sup  >&#x2212;</sup>, and <svg style="vertical-align:-3.13504pt;width:33.450001px;" id="M12" height="14.375" version="1.1" viewBox="0 0 33.450001 14.375" width="33.450001"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,14.375)">
		<g transform="translate(72,-60.5)">
			<text transform="matrix(1,0,0,-1,-71.95,63.67)">
				<tspan style="font-size: 12.50px; " x="0" y="0">B</tspan>
				<tspan style="font-size: 12.50px; " x="8.3395014" y="0">F</tspan>
			</text>

			<text transform="matrix(1,0,0,-1,-56.66,60.55)">
				<tspan style="font-size: 8.75px; " x="0" y="0">4</tspan>
				<tspan style="font-size: 8.75px; " x="4.8800001" y="-8.1199999">−</tspan>
			</text>

		</g>
	</g>
</svg>. The end of the glass-formation region of [DEME][Br]-H<sub  >2</sub>O mixtures is around <svg style="vertical-align:-0.27588pt;width:55.462502px;" id="M13" height="11.0375" version="1.1" viewBox="0 0 55.462502 11.0375" width="55.462502"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,11.0375)">
		<g transform="translate(72,-63.17)">
			<text transform="matrix(1,0,0,-1,-71.95,63.5)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑥</tspan>
				<tspan style="font-size: 12.50px; " x="10.339981" y="0">=</tspan>
				<tspan style="font-size: 12.50px; " x="22.380369" y="0">9</tspan>
				<tspan style="font-size: 12.50px; " x="28.63187" y="0">8</tspan>
				<tspan style="font-size: 12.50px; " x="34.883369" y="0">.</tspan>
				<tspan style="font-size: 12.50px; " x="38.009121" y="0">9</tspan>
			</text>

		</g>
	</g>
</svg> and moves to more water-rich region as compared to those of [DEME][BF<sub  >4</sub>]-H<sub  >2</sub>O (<svg style="vertical-align:-0.27588pt;width:55.462502px;" id="M14" height="11.1625" version="1.1" viewBox="0 0 55.462502 11.1625" width="55.462502"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,11.1625)">
		<g transform="translate(72,-63.07)">
			<text transform="matrix(1,0,0,-1,-71.95,63.4)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑥</tspan>
				<tspan style="font-size: 12.50px; " x="10.339981" y="0">=</tspan>
				<tspan style="font-size: 12.50px; " x="22.380369" y="0">9</tspan>
				<tspan style="font-size: 12.50px; " x="28.63187" y="0">6</tspan>
				<tspan style="font-size: 12.50px; " x="34.883369" y="0">.</tspan>
				<tspan style="font-size: 12.50px; " x="38.009121" y="0">0</tspan>
			</text>

		</g>
	</g>
</svg>) and [DEME][I]-H<sub  >2</sub>O (<svg style="vertical-align:-0.27588pt;width:55.462502px;" id="M15" height="11.225" version="1.1" viewBox="0 0 55.462502 11.225" width="55.462502"  xmlns="http://www.w3.org/2000/svg">
	<g transform="matrix(1.25,0,0,-1.25,0,11.225)">
		<g transform="translate(72,-63.02)">
			<text transform="matrix(1,0,0,-1,-71.95,63.35)">
				<tspan style="font-size: 12.50px; " x="0" y="0">𝑥</tspan>
				<tspan style="font-size: 12.50px; " x="10.339981" y="0">=</tspan>
				<tspan style="font-size: 12.50px; " x="22.380369" y="0">9</tspan>
				<tspan style="font-size: 12.50px; " x="28.63187" y="0">5</tspan>
				<tspan style="font-size: 12.50px; " x="34.883369" y="0">.</tspan>
				<tspan style="font-size: 12.50px; " x="38.009121" y="0">0</tspan>
			</text>

		</g>
	</g>
</svg>) mixtures.

Naohiro Hatano

Osamu Shimada

Tomonori Hanasaki

Glass Transition Behavior of the Quaternary Ammonium-Type Ionic Liquid: <i>N,N</i>-Diethyl-<i>N</i>-methyl-<i>N</i>-(2-methoxyethyl)ammonium Bromide-H<sub>2</sub>O Mixtures

High pressure phase behavior experimental data have been measured for the systems carbon dioxide (CO<sub>2</sub>) + 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF<sub>6</sub>]) and carbon dioxide (CO<sub>2</sub>) + 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF<sub>6</sub>]) + 1-amino-2-phenoxy-4-hydroxyanthraquinone (C.I. Disperse Red 60). Measurements were performed in the pressure up to 18 MPa and at the temperature (323 to 353 K). As reported in the literature, at higher concentrations of carbon dioxide the phase transition pressure increased very steeply. The experimental data for the binary and ternary systems were correlated with good agreement using the Peng-Robinson equation of state. The amount of water in phase behavior of the systems was evaluated.

Helen R. Mazzer

José C. O. Santos

Vladimir F. Cabral

Claudio Dariva

Marcos H. Kunita

Adley F. Rubira

Martin Aznar

Lucio Cardozo-Filho

Phase Behavior at High Pressure of the Ternary System:<svg style="vertical-align:-3.27605pt" height="15.5125" version="1.1" viewBox="0 0 30.8125 15.5125" width="30.8125" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,11.363)"><path id="x43" d="M614 175l29 -10q-33 -109 -57 -154q-121 -26 -184 -26q-90 0 -160.5 29t-112.5 77t-63.5 105.5t-21.5 119.5q0 157 108 253t277 96q36 0 71.5 -5t69 -13.5t36.5 -8.5q15 -102 20 -150l-29 -8q-20 79 -66.5 114t-128.5 35q-119 0 -187.5 -86t-68.5 -207
q0 -140 73.5 -227.5t188.5 -87.5q73 0 119.5 37.5t86.5 116.5z"/></g><g transform="matrix(.017,-0,0,-.017,11.469,11.363)"><path id="x4F" d="M381 665q131 0 226.5 -93t95.5 -239q0 -158 -96 -253t-238 -95q-137 0 -231 95t-94 238q0 142 92.5 244.5t244.5 102.5zM359 629q-89 0 -151 -74.5t-62 -208.5q0 -141 69 -233t175 -92q90 0 150.5 74t60.5 211q0 152 -69 237.5t-173 85.5z"/></g><g transform="matrix(.012,-0,0,-.012,24.188,15.45)"><path id="x1D7D0" d="M453 211h25l-46 -211h-415v23q97 102 151 166q42 49 81 110q51 78 51 148q0 56 -31.5 91.5t-87.5 35.5q-77 0 -122 -90h-28q67 204 223 204q82 0 132 -49.5t50 -133.5q0 -110 -114 -218l-162 -154h140q82 0 107 13q27 13 46 65z"/></g></svg>, Ionic Liquid and Disperse Dye

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Journal of Thermodynamics