@article{wang_fang_2020, title={Retraction dynamics of water droplets after impacting upon solid surfaces from hydrophilic to superhydrophobic}, volume={5}, ISSN={["2469-990X"]}, url={https://doi.org/10.1103/PhysRevFluids.5.033604}, DOI={10.1103/PhysRevFluids.5.033604}, abstractNote={The retraction dynamics of water droplets impacting on surfaces with different wettabilities is studied. Three modes of droplet retractions can be classified as inertial, capillary, and spherical-cap. A new model is proposed to predict the inertial-mode retraction rate of water droplets on different surfaces. The scaling of retraction curves is revised to reveal the similarity behavior of droplet retraction dynamics.}, number={3}, journal={PHYSICAL REVIEW FLUIDS}, author={Wang, Fujun and Fang, Tiegang}, year={2020}, month={Mar} }
 @article{zhao_wang_king_wang_2019, title={Effect of dynamic and static loading during in vitro degradation of a braided composite bioresorbable cardiovascular stent}, volume={250}, ISSN={["1873-4979"]}, DOI={10.1016/j.matlet.2019.04.097}, abstractNote={Bioresorbable cardiovascular stents are usually subjected to dynamic mechanical loads in vivo, which results in a different degradation profile compared to that measured under a static in vitro immersion test. In this study, a dynamic test platform was used to mimic cyclic pulsatile pressure and compared the changes in polymer properties of poly(p-dioxaone)/polycaprolane (PPDO/PCL) braided composite bioresorbable stents (BCBRSs) with static loading and non-loaded environments. The results showed static compressive load accelerated the changes in the hydrolysis process and crystallinity for polymers while the pulsatile pressure increased surface corrosion of the stent struts. Moreover, the degradation rate under dynamic loading was attenuated due to the mitigation of viscous flow of molecule chains and autocatalysis process, compared with that under static loading and non-loaded conditions.}, journal={MATERIALS LETTERS}, author={Zhao, Fan and Wang, Fujun and King, Martin W. and Wang, Lu}, year={2019}, month={Sep}, pages={12–15} }
 @article{wang_wang_fang_2019, title={Flash boiling hollow cone spray from a GDI injector under different conditions}, volume={118}, ISSN={["1879-3533"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85066876915&partnerID=MN8TOARS}, DOI={10.1016/j.ijmultiphaseflow.2019.05.009}, abstractNote={Good spray atomization facilitates fuel evaporation in a gasoline engine, thus contributing to higher fuel efficiency and lower emissions. During certain operations of a gasoline direct injection (GDI) engine, the combination of increased fuel temperature and sub-atmospheric cylinder pressure during injection can lead to flash boiling condition, which promotes droplet breakup and evaporation. In this study, experiments were carried out to study the flash boiling and non-flash boiling spray of a hollow cone GDI piezoelectric injector. By the combination of different temperature and ambient pressure, different superheat degrees (Tf-Tb) and different ambient-to-saturation pressure ratios (Pa/Ps) can be achieved. For a hollow cone injector, the flash boiling spray can cause the cone shape spray to expand, both inwards and outwards. The axisymmetric inward expansion would converge together and form a fast developing plume shape, and the transition point for plume front to appear is around 0.5 for Pa/Ps ratio. When Pa/Ps is larger than 0.5, the spray development is dominated by the injection momentum and the effect of boiling is minor. When Pa/Ps is reduced to below 0.5, the flash boiling effect takes place and changed the spray dynamics. The peak penetration velocity starts increasing rapidly with the superheated degree only, and a good linear relationship exists between plume ratio and the log(Pa/Ps). The spray axial penetration result at a certain time frame shows three regimes: Pa/Ps > 0.5, 0.1 < Pa/Ps < 0.5 and Pa/Ps < 0.1. When Pa/Ps is less than 0.1, flare flash boiling happens and the original spray shape is hardly maintained due to the micro-explosion, meantime the spray axial penetration further increases at a reduced rate. While cases with similar Pa/Ps value can exhibit similar penetration character, cases with similar Tf-Tb value can show some difference.}, journal={INTERNATIONAL JOURNAL OF MULTIPHASE FLOW}, author={Wang, Libing and Wang, Fujun and Fang, Tiegang}, year={2019}, month={Sep}, pages={50–63} }
 @article{wang_yang_wang_zhu_fang_2019, title={Maximum Spread of Droplet Impacting onto Solid Surfaces with Different Wettabilities: Adopting a Rim-Lamella Shape}, volume={35}, ISSN={["0743-7463"]}, url={https://doi.org/10.1021/acs.langmuir.8b03748}, DOI={10.1021/acs.langmuir.8b03748}, abstractNote={Experimental and theoretical investigations are presented for the maximum spread factor (βm) of an impacting droplet onto solid surfaces with contact angle hysteresis. Experiments were conducted with deionized water on six surfaces with different wettabilities. The examined Weber number ( We) falls between 10-1 and 103. A new energetic model adopting a rim-lamella shape is proposed to better represent the droplet shape at the maximum spread. The dynamic contact angle at the maximum spread (θβm) is introduced in the model to account for the curvature of the surrounding rim induced by surface wettabilities. A lamella-rim thickness ratio κ ≈ AWe- B ( A, B > 0) is utilized successfully to depict the droplet shape at different We in a unifying manner. Comprehensive evaluations of the model demonstrate that the theoretical prediction can well recover the features of the experimental observations. The L2-error analysis demonstrates the improvement of the proposed model in predicting βm for a wide range of We = 10-1 to 103: the calculated errors are smaller than 8% for all six surfaces. Moreover, the proposed model can also be applied to predict energy conversion/dissipation during the droplet spreading process and the effects of surface wettability on βm in a reasonable manner. The variation of the percentage of the surface energy and viscous dissipation is consistent with that in previous simulations. The weakness of the current model for predicting βm at extremely low Weber number ( We < 1) is also explained.}, number={8}, journal={LANGMUIR}, publisher={American Chemical Society (ACS)}, author={Wang, Fujun and Yang, Lei and Wang, Libing and Zhu, Yong and Fang, Tiegang}, year={2019}, month={Feb}, pages={3204–3214} }
 @article{fang_wang_2019, title={Unsteady Liquid Film Flow with a Prescribed Free-Surface Velocity}, volume={36}, ISSN={["1741-3540"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85063432348&partnerID=MN8TOARS}, DOI={10.1088/0256-307X/36/1/014701}, abstractNote={A liquid film flow over a flat plate is investigated by prescribing the unsteady interface velocity. With this prescribed surface velocity, the governing Navier–Stokes (NS) equations are transformed into a similarity ordinary differential equation, which is solved numerically. The flow characteristics is controlled by an unsteadiness parameter S and the flow direction parameter Λ. The results show that solutions only exist for a certain range of the unsteadiness parameter, i.e., S ⩽ 1 for Λ = −1 and S ⩽ − 2.815877 for Λ = 1. In the solution domain, the dimensionless liquid film thickness β decreases with S for both the cases. The wall shear stress increases with the decrease of S for Λ = −1. However, for Λ = −1 the shear stress magnitude first decreases and then increases with the decrease of S. There are no zero crossing points for the velocity profiles for both the cases. The profiles of velocity stay either positive or negative all the time, except for the wall zero velocity. Consequently, the vertical velocity becomes a monotonic function. To maintain the prescribed velocity, mass transpiration is generally needed, but for the shrinking film case it is possible to have an impermeable wall. The results are also an exact solution to the full NS equations.}, number={1}, journal={CHINESE PHYSICS LETTERS}, author={Fang, Tiegang and Wang, Fujun}, year={2019}, month={Jan} }
 @article{fang_wang_gao_2019, title={Unsteady magnetohydrodynamic stagnation point flowclosed-form analytical solutions}, volume={40}, ISSN={["1573-2754"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85059591627&partnerID=MN8TOARS}, DOI={10.1007/s10483-019-2463-7}, number={4}, journal={APPLIED MATHEMATICS AND MECHANICS-ENGLISH EDITION}, author={Fang, T. G. and Wang, F. J. and Gao, Bo}, year={2019}, month={Apr}, pages={449–464} }
 @article{fang_wang_gao_2018, title={Liquid film flow over an unsteady moving surface with a new stretching velocity}, volume={30}, ISSN={["1089-7666"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85053521143&partnerID=MN8TOARS}, DOI={10.1063/1.5046479}, abstractNote={In this paper, the liquid film flow over an unsteady moving surface is investigated by considering a new surface moving velocity Uw = Ax/t. With this prescribed surface velocity, the governing Navier-Stokes (NS) equations are transformed into a similarity ordinary differential equation, which is solved numerically for both two-dimensional and axisymmetric flow configurations. The results are an exact solution to the full NS equations. The flow characteristics are controlled by a wall moving parameter, namely, A. It is found that solutions only exist for a certain range of the wall moving parameter, i.e., A ≥ −1/2 for the two dimensional case and A ≥ −1/4 for the axisymmetric case. The dimensionless liquid film thickness (β) first increases with the increase in A in the solution domain, and then, it reaches a peak of βm = 1.3864 at A = 0.90 for the two-dimensional case and βm = 1.5836 at A = 0.53 for the axisymmetric case. For both flow configurations, the liquid film thickness increases with time and there exists flow reversal for a positive value of A. These new solutions can not only provide an exact solution to the NS equations but also be used to explain the liquid film flow occurring in practical applications.}, number={9}, journal={PHYSICS OF FLUIDS}, author={Fang, Tiegang and Wang, Fujun and Gao, Bo}, year={2018}, month={Sep} }
 @article{fang_wang_2018, title={Viscous Slip MHD Flow over a Moving Sheet with an Arbitrary Surface Velocity}, volume={35}, ISSN={["1741-3540"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85058153057&partnerID=MN8TOARS}, DOI={10.1088/0256-307X/35/10/104701}, abstractNote={The magnetohydrodynamic (MHD) flow induced by a stretching or shrinking sheet under slip conditions is studied.Analytical solutions based on the boundary layer assumption are obtained in a closed form and can be applied to a flow configuration with any arbitrary velocity distributions. Seven typical sheet velocity profiles are employed as illustrating examples. The solutions to the slip MHD flow are derived from the general solution and discussed in detail. Different from self-similar boundary layer flows, the flows studied in this work have solutions in explicit analytical forms. However, the current flows require special mass transfer at the wall, which is determined by the moving velocity of the sheet. The effects of the slip parameter, the mass transfer at the wall, and the magnetic field on the flow are also demonstrated.}, number={10}, journal={CHINESE PHYSICS LETTERS}, author={Fang, Tiegang and Wang, Fujun}, year={2018}, month={Oct} }