NUMERICAL SIMULATION OF TWO-PHASE GRAVITY CURRENTS OVER A POROUS SUBSTRATE

Based on shallow-water approximations the governing equations for twodimensional two-phase gravity currents over a porous substrate and some appropriate boundaryconditions were introduced. With on characteristic interpolations the numerical boundary conditionswere introduced and a series of exact solutions were constructed. Numerical a-nalysis were made byusing the two-step Lax scheme, second-order TVD scheme, third-order ENO scheme and fifth-order WE NOscheme combined with second- and third-order TVD-Runge-Kutta method is given. It is found that forpractice applications the second-order TVD scheme combined with the second-order TVD- Runge- Kuttamethod is an economical and suitable choice.

Design strategy of porous elastomer substrate and encapsulation forinorganic stretchableelectronics

The emergence of stretchable electronic technology has led to the development of many industries and facilitated many unprecedented applications,owing to its ability to bear var-ious deformations.However,conventional solid elastomer sub-strates and encapsulation can severely restrict the free motion and deformation of patterned interconnects,leading to poten-tial mechanical failures and electrical breakdowns.To address this issue,we propose a design strategy of porous elastomer substrate and encapsulation to improve the stretchability of serpentine interconnects in island-bridge structures.The ser-pentine interconnects are fully bonded to the elastomer sub-strate,while segments above circular pores remain suspended,allowing for free deformation and a substantial improvement in elastic stretchability compared to the solid substrates.The pores ensure unimpeded interconnect deformations,and mod-erate porosity provides support while maintaining the initial planar state.Compared to conventional solid configurations,finite element analysis(FEA)demonstrates a substantial enhancement of elastic stretchability(e.g.=9 times without encapsulation and=7 times with encapsulation).Uniaxial cyc-lic loading fatigue experiments validate the enhanced elastic stretchability,indicating the mechanical stability of the porous design.With its intrinsic advantages in permeability,the pro-posed strategy has the potential to offer insightful inspiration and novel concepts for advancing the field of stretchable inorganic electronics.

Effect of Flow Field Geometry on Hydrodynamics of Flow in Redox Flow Battery

This study computationally investigates the hydrodynamics of different serpentine flow field designs for redox flow batteries,which considers the Poiseuille flow in the flow channel and the Darcy flow porous substrate.Computational Fluid Dynamics(CFD)results of the in-house developed code based on Finite Volume Method(FVM)for conventional serpentine flow field(CSFF)agreed well with those obtained via experiment.The deviation for pressure drop(ΔP)was less than 5.1%for all the flow rates,thus proving the present CFD analysis’s validity on the modified variation of serpentine flow fields.Modified serpentine flow field-2(MSFF2)design provided least pressure drop across the channel and maximum velocity penetration across the porous substrate when compared to the other designs.This increases its wetting ability,which is very important in terms of mass transfer over potential for electrochemical reaction happening in the porous substrate to achieve effective electrochemical cell performance.

Assembly of flower-like VS_(2)/N-doped porous carbon with expanded(001)plane on rGO for superior Na-ion and K-ion storage

VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer spacing(0.57 nm)of VS2 generally determines high ion diffusion barrier and large volume variation,resulting in unsatisfactory electrochemical performance of SIBs and PIBs.In this work,flower-like VS_(2)/N-doped carbon(VS_(2)/N-C)with expanded(001)plane is grown on reduced graphene oxide(rGO)via a solvothermal and subsequently carbonization strategy.In the VS_(2)/N-C@rGO nanohybrids,the ultrathin VS2"petals"are alternately intercalated by the N-doped porous carbon monolayers to achieve an expanded interlayer spacing(1.02 nm),which can effectively reduce ions diffusion barrier,expose abundant active sites for Na+/K+intercalation,and tolerate large volume variation.The N-C and rGO carbonous materials can significantly promote the electrical conductivity and structural stability.Benefited from the synergistic effect,the VS2/N-C@rGO electrode exhibits large reversible capacity(Na+:407 mAh·g^(-1) at 1 A·g^(-1);K^(+):334 mAh·g^(-1) at 0.2 A·g^(-1)),high rate capacity(Na+:273 mAh·g^(-1) at 8 A·g^(-1);K+:186 mAh·g^(-1) at 5 A·g^(-1)),and remarkable cycling stability(Na+:316 mAh·g^(-1) at 2 A·g^(-1) after 1,400 cycles;K^(+):216 mAh·g^(-1) at 1 A·g^(-1) after 500 cycles).