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Showing 3 results for Temperature Effect
Amer Alizadeh, Seyed Ali Mirbozorgi,
Volume 12, Issue 3 (8-2012)
Abstract
In this paper the effects of the inlet fluid temperature on the electro-osmotic flow pattern in a two-dimensional microchannel with constant walls temperature is investigated with solving the governing equations by the Lattice Boltzmann method. The main objective of this research is to study the effects of temperature variations on the distribution of ions and consequently internal electric potential and velocity field. For make possible to use the Boltzmann ion distribution equation, cup mean temperature for every cross section of the microchannel is used. At the used Lattice Boltzmann method, LBGK model for modeling the Boltzmann collision function and the Zou-He boundary conditions method for velocity field has been used. Wang model for solving the Poisson-Boltzmann and He-Chen model for solving the energy equation has been used. The results show that, with increase the temperature difference between the inlet flow and the walls, the electro-osmotic flow rate increases. Also, observed that with decrease the external electric potential and the electric double layer thickness and increase the temperature difference at the inlet zone of the microchannel, a region with return flow is formed which can be used for controlling the internal flow pattern.
Mina Kamali Moghaddam, Masoud Tahani,
Volume 17, Issue 3 (5-2017)
Abstract
The purpose of this paper is to deal with fracture behavior of carbon nanotubes with presenting a revised structural molecular mechanics model in the finite element method. Structural molecular mechanics modified model, uses a three-dimensional beam element with general section to make nanotube structural model in which bending stiffness and inversion are defined independently. In analysis which are done, a bridged carbon nanotube with constant strain rate is examined under tensile stress until the failure of nanotube. Carbon-carbon bonds behavior has been assumed nonlinearly and will be ruptured when the strain reaches 19%. It is predicted that fracture behavior in carbon nanotubes depends on the environment temperature due to mechanical behavior of carbon nanotube's bonds. Based on the present research, we found that by increasing the temperature, Poisson's ratio increases and Young's modulus decreases. Further, it can be said while the temperature increases, both the fracture ultimate strain and stress decrease. Finally, a nonlinear relationship is presented in which the constants depend on chirality of the carbon nanotubes.
Volume 25, Issue 3 (5-2023)
Abstract
This study was conducted to examine the sensitivity of weather parameters and CO2 concentration to wheat production under two irrigation regimes viz. full irrigation and limited irrigation, using CERES-Wheat model. Field experiment data from the 2016-17 and 2017-18 rabi seasons on wheat cultivar HD-2967 with three sowing dates and five irrigation regimes were used to calibrate and validate the CERES-Wheat crop simulation model. Validation results indicated very good agreement between simulated and observed values under five, four, and three irrigations regimes as compared to lower irrigation regimes. Under full irrigation and limited irrigation, grain yield sensitivity to incremental unit of mean temperature from 1 to 3°C revealed a decrease of 6 to 22% and 8 to 16%, respectively. Temperature decreases of 1-3°C resulted in a gradual increase in yield of 10-28 and 6.5- 20%, respectively, under full and limited irrigation. The combined effect of higher mean temperature and lower solar radiation revealed that wheat yield was more sensitive to temperature than solar radiation. Furthermore, the combined effect of mean temperature and CO2 level revealed that higher levels of CO2 concentration yielded the greatest benefits with a 1 °C increase in temperature, but further increases in temperature reduced the beneficial effect of elevated CO2 level under both irrigation conditions.
