In this paper,we develop a fully discrete virtual element scheme based on the local pressure projection stabilization for a three-field poroelasticity problem with a storage coefficient c00.We not only provide the wel...In this paper,we develop a fully discrete virtual element scheme based on the local pressure projection stabilization for a three-field poroelasticity problem with a storage coefficient c00.We not only provide the well-posedness of the proposed scheme by proving a weaker form of the discrete inf-sup condition,but also show optimal error estimates for all unknowns,whose generic constants are independent of the Lam´e coefficient.Moreover,our proposed scheme avoids pressure oscillation and applies to general polygonal elements,including hanging-node elements.Finally,we numerically validate the good performance of our virtual element scheme.展开更多
As the power density of the power transmission device increases,heat exchangers are required to dissipate more heat and provide better flow resistance in the limited space of the vehicle.In this study,the synergy mech...As the power density of the power transmission device increases,heat exchangers are required to dissipate more heat and provide better flow resistance in the limited space of the vehicle.In this study,the synergy mechanism of the temperature field,pressure field,and velocity field in the serrated fin channel of the plate-fin heat exchanger(PFHX)was thoroughly analyzed under the guidance of the three-field synergy principle.This study also quantitatively revealed the distribution of the angleθbetween the temperature gradient and velocity,and the angleαbetween the pressure gradient and velocity.For the regions in the channel whereθwas too large(i.e.,poor synergy between temperature and velocity fields)andαwas too small(i.e.,poor synergy between pressure and velocity fields),high-efficiency and low-resistance fin structures were proposed.The performance improvement of the new structures was quantified using the comprehensive heat transfer and flow resistance performance evaluation plot in the three-field synergy standard.The results indicate that the new structures improve the synergy of the three fields in the channel.When the air velocity is 15 m s^(-1),the average synergy angleθmbetween the temperature gradient and the velocity of the two structures,changing the inlet flow direction and the slotted fin,decreases from 83.4° to 80.3° and 82.8°,respectively.The outlet temperature increases by 2.3 and 1.6 K,respectively,compared to the basic structure,indicating enhanced the heat transfer of the PFHX.By changing the shape of the fin cross-section,the average synergy angleαmbetween the pressure gradient and the velocity increased from 143.6°to 150.8°,whileθmincreased by only 0.6°.The pressure loss was reduced by 15.2% compared to the basic structure,resulting in a significant decrease in pressure drop while maintaining essentially the same heat transfer performance.Meanwhile,the optimized PFHX can increase the heat transfer rate by 0.2%–8% under identical pump power.This work provides guidance on selecting high-efficiency and low-resistance vehicle-mounted PFHXs.展开更多
基金supported in part by the National Natural Science Foundation of China(Grant No.12371405).
文摘In this paper,we develop a fully discrete virtual element scheme based on the local pressure projection stabilization for a three-field poroelasticity problem with a storage coefficient c00.We not only provide the well-posedness of the proposed scheme by proving a weaker form of the discrete inf-sup condition,but also show optimal error estimates for all unknowns,whose generic constants are independent of the Lam´e coefficient.Moreover,our proposed scheme avoids pressure oscillation and applies to general polygonal elements,including hanging-node elements.Finally,we numerically validate the good performance of our virtual element scheme.
基金supported by the National Science and Technology Major Project of China(Grant No.J2019-Ⅲ-0021-0065)the Inner Mongolia Science and Technology Major Project(Grant No.2021ZD0036)the Key R&D Special Program of Shaanxi Province(Grant No.2022GXLH-01-04)。
文摘As the power density of the power transmission device increases,heat exchangers are required to dissipate more heat and provide better flow resistance in the limited space of the vehicle.In this study,the synergy mechanism of the temperature field,pressure field,and velocity field in the serrated fin channel of the plate-fin heat exchanger(PFHX)was thoroughly analyzed under the guidance of the three-field synergy principle.This study also quantitatively revealed the distribution of the angleθbetween the temperature gradient and velocity,and the angleαbetween the pressure gradient and velocity.For the regions in the channel whereθwas too large(i.e.,poor synergy between temperature and velocity fields)andαwas too small(i.e.,poor synergy between pressure and velocity fields),high-efficiency and low-resistance fin structures were proposed.The performance improvement of the new structures was quantified using the comprehensive heat transfer and flow resistance performance evaluation plot in the three-field synergy standard.The results indicate that the new structures improve the synergy of the three fields in the channel.When the air velocity is 15 m s^(-1),the average synergy angleθmbetween the temperature gradient and the velocity of the two structures,changing the inlet flow direction and the slotted fin,decreases from 83.4° to 80.3° and 82.8°,respectively.The outlet temperature increases by 2.3 and 1.6 K,respectively,compared to the basic structure,indicating enhanced the heat transfer of the PFHX.By changing the shape of the fin cross-section,the average synergy angleαmbetween the pressure gradient and the velocity increased from 143.6°to 150.8°,whileθmincreased by only 0.6°.The pressure loss was reduced by 15.2% compared to the basic structure,resulting in a significant decrease in pressure drop while maintaining essentially the same heat transfer performance.Meanwhile,the optimized PFHX can increase the heat transfer rate by 0.2%–8% under identical pump power.This work provides guidance on selecting high-efficiency and low-resistance vehicle-mounted PFHXs.
