Experimental investigation into effects of the natural polymer and nanoclay particles on the EOR performance of chemical flooding in carbonate reservoirs

This paper aims to investigate the tragacanth gum potential as a natural polymer combined with natural clay mineral(montmorillonite,kaolinite,and illite)nanoparticles(NPs)to form NP-polymer suspension for enhanced oil recovery(EOR)in carbonate reservoirs.Thermal gravimetric analysis(TGA)tests were conducted initially in order to evaluate the properties of tragacanth gum.Subsequently,scanning electron microscopy(SEM)and energy-dispersive X-ray(EDX)tests were used to detect the structure of clay particles.In various scenarios,the effects of natural NPs and polymer on the wettability alteration,interfacial tension(IFT)reduction,viscosity improvement,and oil recovery were investigated through contact angle system,ring method,Anton Paar viscometer,and core flooding tests,respectively.The entire experiment was conducted at 25,50,and 75℃,respectively.According to the experimental results,the clay minerals alone did not have a significant effect on viscosity,but the addition of minerals to the polymer solution leads to the viscosity enhancement remarkably,resulting mobility ratio improvement.Among clay NPs,the combination of natural polymer and kaolinite results in increased viscosity at all temperatures.Considerable wettability alteration was also observed in the case of natural polymer and illite NPs.Illite in combination with natural polymer showed an ability in reducing IFT.Finally,the results of displacement experiments revealed that the combination of natural polymer and kaolinite could be the best option for EOR due to its substantial ability to improve the recovery factor.

The role of the fiber ply configurations on the biomechanics of the hip prosthesis

The total hip replacement is the only approved procedure for restoring a degenerated hip joint through operation.The life span of a prosthesis could depend on the geometry and material properties of the implant.This study aims to analyze the biomechanics of the carbon/polyetheretherketone(PEEK)composite prosthesis having three different fiber ply configurations compared to traditional stainless steel(SS)ones.The implant-bone system was established and subjected to a load from the head of the femur and abductor muscle sides.The stresses and strains in the implant-bone systems were calculated and compared.The results revealed lower stresses and strains in composite prostheses compared to SS ones.The fiber ply orientation of the carbon/PEEK composite prosthesis is shown to be a key asset in stress and strain distribution of the 13 implant-bone systems.The fiber plies which orientated multidirectionally with−45 and+45 degrees exhibited uniform stress and strain distributions.The results suggested the advantage of using composite prostheses in implant designs as they not only invoke lower stresses and strains in the implant-bone system but also amplify the life span of implants in the body.

A numerical analysis on different-generation prototypes of ventricular assist device

The ventricular assist device(VAD)assists the patients with heart diseases for limited and prolonged periods.This device synchronizes with normal heart activities to help foster its performance.Consequently,its sensitive design requires high accuracy.The pumps are the essential part of every VAD which should operate in wide ranges of flow and pressure.As there are various types of VAD under different designs,it is neither practical nor plausible to experimentally/clinically investigate their performances.Therefore,in the concurrent study,a numerical study was carried out on four different generation prototypes of VAD pumps for reaching an optimum design.Using computational fluid dynamics(CFD)method,the software derived,showed and streamlined the flow field shear stress both inside the VAD and its blades.Furthermore,the vortices and flow rate-pressure curves were observed.The results showed that the curved blade pumps operate better compared to that of the straight blade types,concerning the provision of enough pressure and less damage to the red blood cells.The results have implications not only for comparing different types of VAD designs but also for understanding the resulted shear stresses and pressures as a result of the blade’s structure.