Acceleration of Lattice Boltzmann Simulation via OpenACC

The parallel acceleration of well-developed serial codes for numerical simulations of fluid dynamic problems is implemented in this paper. To solve the flow field,the lattice Boltzmann method( LBM) is used. The OpenACC( OpenACCelerator) application programming interface,which is a relatively new standard for parallel computation,is adopted to perform the acceleration. By parallelizing the computation intensive loops and decreasing some meaningless data movement,the serial codes based on LBM are obviously accelerated. Several benchmark problems are considered and then simulated through the OpenACC programming model to assess performance and computational efficiency. After optimization,a reasonable speedup is obtained in comparison with the original version.

Insulin peptides and their receptors regulate ovarian development and oviposition behavior in Diaphorina citri

Diaphorina citri is an important vector of Citrus Huanglongbing(HLB)disease.After feeding on young host plant shoots,the population of D.citri can increase significantly.Females also only lay eggs on young shoots.However,there are few studies on the mechanism of this phenomenon.Exogenous nutrient signals can affect the insulin signaling system of D.citri after feeding on young shoots.In this study,the expression of upstreamfactors DclLPl,DclLP2,and DclR in the insulin signaling system of D.citri was upregulated after feeding on young shoots.After being silenced by RNA interference technology,the results showed that the number of oviposited eggs of D.citri was significantly decreased and the ovarian development was inhibited with severe vacuolation.In addition,detection using quantitative reverse transcription-polymerase chain reaction showed that the upstream regulatory gene DcRheb of the target of rapamycin(TOR)pathway and the downstream reproduction-related DcVg gene were also significantly downregulated.These results suggest that feeding upon young shoots may upregulate the expression levels of upstream factors DclLPl,DclLP2,and DclR in the insulin signaling system.The signal will be through upregulating the expression of DcRheb,an upstream gene of the TOR signaling pathway.This in turn influences yolk metabolism,which eventually causes the ovaries of female D.citri to mature and therefore initiate oviposition behavior.

Aerodynamic Performance of a Flapping Foil with Asymmetric Heaving Motion near a Wall

The effect of asymmetric heaving motion on the aerodynamic performance of a two-dimensional flapping foil near a wall is studied numerically. The foil executes the heaving and pitching motion simultaneously. When the heaving motion is symmetric, the mean thrust coefficient monotonically increases with the decrease in mean distance between foil and wall. Meanwhile, the mean lift coefficient first increases and then decreases sharply. In addition, the negative mean lift coefficient appears when the foil is very close to the wall. After the introduction of asymmetric heaving motion, the influence of wall effect on the force behavior becomes complicated. The mean thrust coefficient is enhanced when the duration of upstroke is reduced. Moreover, more and more enhancement can be achieved when the foil approaches the wall gradually. On the other hand, the positive mean lift coefficient can be observed when the duration of downstroke is shortened. By checking the flow patterns around the foil, it is shown that the interaction between the vortex shed from the foil and the wall can greatly modify the pressure distribution along the foil surface. The results obtained here might be utilized to optimize the kinematics of the Micro Aerial Vehicles （MAVs） flying near a solid wall.