Deep Closure Research Articles

Experimental investigation on the water-entry characteristics of the structure passing through the broken ice field

In this study, experiments are conducted on the process of a structure entering water under an ice-free environment and a broken ice field environment with three different broken ice densities based on a water-entry experimental platform. The influences of the broken ice field environment and different broken ice densities on the variations in the cavity morphology and movement features of water entry into the structure are investigated. The results show that the broken ice field environment postpones the surface closure of the cavity, leading to an increase in the size of the closed cavity, which, in turn, affects the cavity collapse process, slows down the overall collapse of the cavity, and is conducive to the cavity formation of the structure. In addition, when the density of broken ice is 30%, the influence of the broken ice field on the variations in the cavity morphology is not significant. When the density of broken ice increases to 70%, the expansion, cavity closure, and collapse are significantly different from those in an ice-free environment. Necking and deep closure occur. Some broken ice is drawn into the cavity, accelerating the cavity collapse. The effect of the broken ice field environment on the motion stability of the structure entering the water increases with an increase in broken ice density. When the density of broken ice increases to 50 and 70%, owing to the direct collision between the structure and broken ice, mutual forces and momentum transfer are generated. This results in a horizontal displacement of the trajectory of the structure, a sudden decrease in velocity, and an acceleration of velocity attenuation, ultimately affecting the motion stability and drag reduction characteristics of the structure.

Investigation of free surface effect on the cavity expansion and contraction in high-speed water entry

The evolution of the water-entry cavity affects the impact load and the motion of the body. This paper adopts the Eulerian finite element method for multiphase flow for simulations of the high-speed water-entry process. The accuracy and convergence of the numerical method are verified by comparing it with the experimental data and the results of the transient cavity dynamics theory. Based on the results, the representative characteristics of the cavity are discussed from the perspective of the cavity cross-section. It is found that the asymmetry of the cavity expansion and contraction durations is related to the motion of the free surface and the closure of the cavity. The uplift of the free surface suppresses cavity expansion, while the jet generated from free surface closure accelerates cavity contraction. The duration of the contraction of the cavity near the free surface is shorter than the expansion duration due to the change in the velocity distribution caused by the free surface motion. The necking phenomenon during deep closure leads to an increase in the internal pressure of the cavity, prolonging cavity contraction near the deep closure area. This work provides new insights into the cavity dynamics in high-speed water entry.

Evaluation of the Cavitation Fluid Characteristics of the Bullet across the Medium into the Water at Different Velocities

This paper studies the evolution and fluid distribution characteristics of a high-speed projectile’s cavity in the water based on joint research, a method involving experiment and numerical simulation. Specifically, we develop an experimental platform and a numerical calculation model for a high-speed projectile to observe its initial cavity evolution characteristics in the water at different velocities and close ranges. Additionally, this work investigates the evolution mechanism of the cavitation process and its fluid distribution law inside the cavity and studies the evolution characteristics of the cavitation stage under different velocities. The results reveal that after the projectile enters the water, the cavity is gourd-shaped and symmetrical, with a necking phenomenon at the tail and the cavity falling off. The cavitation process can be divided into the surface closure, saturation, deep closure, and collapse stages according to the fluid distribution changes in the cavity. Suppose the projectile has a certain speed with the water, its velocity increases. In that case, the cavity generation rate decreases, the growth rate of the water vapor volume in the cavity decreases, the peak water vapor volume content reduces, and the volume of air in the saturation phase of the cavity becomes increases having a range of 6% to 9%. Additionally, the cavity surface closure dimensionless time grows logarithmically as the velocity changes from 0 m/s to 500 m/s, the cavity saturation dimensionless time decreases approximately linearly, and the cavity depth closure dimensionless time is unaffected by velocity changes.

Translated article] Wound closure after knee and hip replacement (TKA and THA): Survey results on the clinical practice in Spain

Background and objectiveIn orthopaedic surgery, it is clear that an optimal standardised closure technique has not yet been developed. Locally, there are no objective data describing the standard surgical practice in wound closure. The aim of this study is to analyse the clinical practice of surgical wound closure in orthopaedic surgery by means of a survey of a representative local sample and thus obtain information on the context of closure in Spain. Material and MethodAn ad hoc group of specialists in orthopaedic surgery and traumatology was formed. The group of experts, after analyzing the literature, developed a questionnaire of 32 closed multiple-choice questions divided into the following blocks: hemostasis, surgical wound closure (deep, superficial, and cutaneous), and dressings. ResultsA total of 471 surgeons responded to the survey completely and with sufficient information to perform the descriptive analysis. 79% believe that ATX can influence the decrease in surgical site infection rate. 96% believe that the type of deep closure at the level of the arthrotomy could influence outcomes and complications after hip and/or knee replacements. 85% believe that the type of shallow closure at the subcutaneous level may influence outcomes and complications after hip and/or knee replacement. 64% of surgeons use single-use incisional negative pressure therapy for the treatment of surgical wound complications (seroma, prolonged drainage, dehiscence). ConclusionsThere is a high level of variability in wound closure in our setting and a low level of training on the subject. The authors recommend that the different scientific societies invest resources to improve training in this field and reduce the percentage of surgeons who are considered inadequately trained, as well as adapting closure techniques to those considered gold standard according to the evidence.

Cavity evolution of the high-speed cylinder entering the water under different ice-hole diameter constraints

In this study, experimental research on the oblique water-entry process of the high-speed cylinder under the ice-free condition and three different ice-hole diameter conditions based on the high-speed photography technology is carried out. The experimental repeatability is verified. The influence of the ice-hole constraint on the evolution process of the cavity of the cylinder is investigated by dividing in three stages: the cavity expansion stage, the surface closure stage, and the deep closure stage. Besides, the evolution characteristics of the cavity under four different experimental conditions are studied. Results show that during the cavity expansion stage, the cavity expansion is constrained by the ice-hole. The left side of the cavity near the free surface is curved. With the increase of the ice-hole diameter, the curvature of the left side profile of the cavity gradually decreases. The liquid around the water-entry point impacts the inner wall of the ice-hole to generate a reflective flow. During the surface closure stage, the impact of the reflective flow inhibits the contraction of the right side of the cavity wall, which further induces that the surface closure of the cavity is delayed. Besides, under the influence of smaller ice-hole, the right tail of the cavity wall is impacted by the reflective flow and a local impact collapse occurs. As the diameter of the ice-hole increases, the right tail of the cavity wall is folded but does not collapse significantly, and independent surface closure jet and reflective flow can be observed. During the deep closure stage, under the ice-hole constraint, in addition to the puff-off collapse, it can be found that the shedding collapse is accompanied by the local impact collapse. The occurrence of cavity deep closure of the cylinder is accelerated.

Cierre de herida en cirugía protésica de rodilla y cadera (PTR y PTC): Resultados de una encuesta sobre la práctica clínica en España

Background and objectiveIn orthopedic surgery, it is clear that an optimal standardized closure technique has not yet been developed. Locally, there are no objective data describing the standard surgical practice in wound closure. The aim of this study is to analyze the clinical practice of surgical wound closure in orthopedic surgery by means of a survey of a representative local sample and thus obtain information on the context of closure in Spain. Methodan ad hoc group of specialists in orthopedic surgery and traumatology was formed. The group of experts, after analyzing the literature, developed a questionnaire of 32 closed multiple-choice questions divided into the following blocks: hemostasis, surgical wound closure (deep, superficial, and cutaneous), and dressings. ResultsA total of 471 surgeons responded to the survey completely and with sufficient information to perform the descriptive analysis. 79% believe that ATX can influence the decrease in surgical site infection rate. 96% believe that the type of deep closure at the level of the arthrotomy could influence outcomes and complications after hip and/or knee replacements. 85% believe that the type of shallow closure at the subcutaneous level may influence outcomes and complications after hip and/or knee replacement. 64% of surgeons use single-use incisional negative pressure therapy for the treatment of surgical wound complications (seroma, prolonged drainage, dehiscence). ConclusionsThere is a high level of variability in wound closure in our setting and a low level of training on the subject. The authors recommend that the different scientific societies invest resources to improve training in this field and reduce the percentage of surgeons who are considered inadequately trained, as well as adapting closure techniques to those considered gold standard according to the evidence.

Experimental investigation on the multiphase flow characteristics of oblique water entry of the hollow cylinders

The oblique water entry of the hollow cylinders with various inner diameters has been investigated experimentally. The multiphase flow characteristics of the cavity, through-hole jet and multiscale bubbles have been revealed and discussed. In the experimental setup, a high-speed photography technique is used to capture the process of water entry based on digital video images. The results show that the fluid flows to the inside and outside of the hollow cylinder along the flow separation position, the through-hole jet and cavity are formed. The deep closure mode of the cavity pinched off by line contact appears, the upper cavity moves upward and the secondary jet is formed, and the lower cavity presents the evolution process of stable transparent surface, fluctuating rippling surface, blurry broken surface and collapse. Three bubble clusters are formed due to the closure and pinching off of the cavity, the breaking up of the through-hole jet, and the blurry broken evolution of the lower cavity, and are shedding upward along the moving paths of the upper cavity, the tail and the head of the hollow cylinder, respectively. Moreover, a parametric study is conducted on the effects of inner diameters on the multiphase flow structure and dynamic characteristics.

Comparación entre suturas para cierre profundo y superficial en reemplazo total de rodilla: seguimiento a un año

IntroductionDifferent materials and techniques have been developed for superficial and deep closure in total knee replacement (TKR), but there is no solid evidence that allows to recommend a specific technique that decreases the surgical post-operative complications. The purpose of this study is to compare the use of two deep closure techniques (barbed suture vs. braided absorbable suture) and superficial (staples vs. polypropylene suture) in TKR. Materials and methodsAn observational retrospective study was carried out in 240 patients. Those individuals were excluded with previous open knee surgery, arthrofibrosis, patients who underwent TKR due to tumor lesions or a follow up for less than one year. ResultsThe skin was closed in 176 patients with staples and in 64 patients with Prolene®. Deep closure was performed with Stratafix® in 164 patients and with Vicryl® in 75 patients. Also, complications related to the wound and functionality were recorded in the first postoperative year. Superficial infection for closure with prolene presented an HR in favor of 2.6 with a confidence interval (CI) of 95%=1.1–6.2; p=0.029 and in deep closure a HR in favor of Vicryl® of 0.22, 95% CI=0.96–5.8; p=0.05 ConclusionsThis study demonstrated a significant increase in the incidence of superficial infection after TKR when deep closure is performed with barbed sutures and superficial closure with polypropylene suture. However, there were no significant differences in other complications related with the wound neither postoperative functionality with the different superficial and deep closure techniques that were evaluated.

Open Reduction and Internal Screw Fixation of Transitional Ankle Fractures in Adolescents.

Surgical treatment of a triplane fracture is indicated if there is >2 mm articular displacement of the distal aspect of the tibia or if the fracture pattern is deemed unstable following closed reduction and casting. Preoperative planning (Step 1) involves the use of radiographs and computed tomography scans to determine accurate fracture classification, the intended reduction maneuver, possible blocks to reduction, and screw trajectory and length. Room setup and patient positioning (Step 2) include placing the patient in the supine position with a bump under the hip, as well as the placement of a ramp or stack of blankets under the affected limb and adequate general anesthesia with muscle relaxation to facilitate reduction. Incision and surgical exposure (Step 3) is performed with use of an anterior ankle incision at the anatomic plane between the extensor hallucis longus and extensor digitorum longus, protecting the neurovascular bundle (i.e., the anterior tibial artery and deep peroneal nerve). Open reduction and assessment of reduction (Step 4) begins by removing any soft tissue, such as the periosteum, that may be interposed in the fracture site precluding a reduction. The ankle is then put through internal rotation and dorsiflexion in order to reduce the fracture, utilizing direct visualization through the incision and fluoroscopy to verify reduction with <2 mm articular step-off. Screw placement (Step 5) typically involves a 2-screw construct, with 1 screw starting at the anterolateral distal tibial epiphysis aiming medially (and staying within the epiphysis) and a metaphyseal screw aiming from the anterior metaphysis to the posterior Thurston-Holland fragment. Closure and immobilization (Step 6) usually involve a layered skin closure, as no deep closure is necessary in most cases. A below-the-knee cast is applied with the ankle in neutral dorsiflexion. Nonoperative treatment typically involves closed reduction and long-leg cast immobilization. Surgical treatment with reduction and screw fixation of triplane fractures is indicated for patients with >2 mm articular displacement or >3 mm physeal displacement of the distal aspect of the tibia. Achieving and maintaining reduction with screw fixation within these tolerances helps decrease the chance of arthritis development by 5 to 13 years postoperatively5,7. Following treatment of a triplane fracture with reduction and screw fixation, full ankle range of motion and normal growth are anticipated. Postoperative follow-up continues until skeletal maturity or until 1 year postoperatively with evidence of continued growth by Park-Harris lines on sequential radiographs. Short-term recovery is expected to be excellent, and long-term results are expected to be good as long as <2 mm articular reduction is achieved and maintained5,7. General anesthesia with muscle relaxation helps with closed or open reduction.Computed tomography is valuable for determining the maximum articular displacement and for 3D surgical planning for screw trajectories.Be aware of the periosteum and perichondrial ring as possible soft-tissue blocks to reduction, and do not hesitate to visualize the periosteum with an open technique to achieve anatomic reduction. AITFL = anterior inferior tibiofibular ligamentAP = anteroposteriorCT = computed tomography.

Numerical investigation on the cavity dynamics and multiphase flow field evolution for water entry of vertical cylindrical shell

Water entry of vertical cylindrical shell is a nonlinear and unsteady process that involves the coupling of multiphase flow. In this paper, a numerical simulation of the water entry of vertical cylindrical shell is carried out with an objective to examine the physical mechanism of flow characteristics due to the effect of inner diameter. The numerical results are validated and verified against the experimental data. From the flow characteristics, the phenomena of cavitation closure can be identified as the cavity evolution the deep closure, the semi-closed mode and the non-cavity closure. The effect of inner diameter of cylindrical shell shows to have a significant influence on the cavity closure mode and time, and its geometry profile. The parametric study showed that the acceleration of cylindrical shell decreases with increasing inner diameter in the process of water entry. The formation of pressure, velocity and multi-scale vortices indicate the complex distribution of these components changing with space and time.

Correcting Nipple Inversion Simultaneously with Implant Augmentation of the Breast, Using “Pirelli” Technique

Background:Most techniques of isolated nipple inversion correction are well published. Simultaneous breast augmentation with nipple inversion correction is less often found in the literature. Previously, nipple inversion correction was thought to be performed as a staged procedure after other breast operations. We present a study of 19 patients and 34 breasts who had concomitant breast augmentation and nipple inversion correction treated with a “Pirelli” technique to assess the complication rates and the rate of recurrence of inversion.Methods:The Pirelli technique was used, involving division of lactiferous ducts and deep closure of breast tissue before closure. An external “Pirelli tire” was then applied and secured circumferentially around the nipple–areolar complex, which helped to maintain eversion of the nipple after 1 week. Patients were then followed up with specific postoperative instructions to ensure wound healing and maintenance of eversion.Results:Nineteen patients were included where 34 breasts were involved. Eighteen patients had primary breast implants. The recurrence rate was 5.9%, involving 2 patients who had unilateral recurrences. These patients were managed with the same technique and had no further recurrences. Two patients successfully breastfed at a median time of 10 years postoperatively.Conclusion:Simultaneous breast mammoplasty with nipple inversion correction using the Pirelli technique is safe with low complication rates and high long-term patient satisfaction.

An investigation into container constraint effects on the cavity characteristics due to high-speed projectile water entry

In this paper, the influence of container dimension constraints on the cavity expansion characteristics were preliminary investigated through series of high-speed water-entry experiments with velocity in the range of 80–470 m/s. Particular attention is given to the characteristics of cavity evolution, surface and deep closure, average cavity wall velocity and the drag coefficient under container constraints. In the test configurations, three size cylindrical-shaped containers were employed, a digital high-speed camera system is used to photograph the projectile motion and cavity expansion within the water-filled containers. Experimental results show that the cavity in a larger container will reach a larger radius and collapses later than the cavity in a much smaller container. The container size has little effect on the time of surface closure and the location of deep closure but more on the time of deep closure. Moreover, it is found that as the container size decreases to a magnitude of the cavity diameter, the projectile velocity attenuation will be strongly affected by the container constraint. The objective of the present study is to provide original dynamic data for studying the nature of hydrodynamic ram caused by the cavity expansion in subsequent work.

Investigations on the vertical water-entry of a hollow cylinder with deep-closure pattern

The vertical water-entry of a low-speed hollow cylinder is studied numerically and experimentally in this work. The special flow characteristics of the hollow cylinder during the water entry have been revealed and discussed. Different from water entry of typical solid bodies, a through-hole jet with a bubble attached at the top forms at the impact stage, and the deep closure occurs around the circumference of the through-hole jet, and the secondary jet generated during the pinch-off has the shape of a hollow thin cylinder. Moreover, its head cavity includes both external and internal parts, and the internal cavity is more complicated and instable. The reasons for above differences have also been explained and discussed. Furthermore, the numerical results agree well with corresponding experimental data.

Deep and Superficial Closure.

All operative interventions in plastic surgery have one thing in common: closure of an incision or wound at the conclusion of the procedure. For many years, the only option to accomplish this task was the use of sutures. Today's surgeon, however, has many more options available, ranging from smooth to barbed suture, external to internal staples, internal to external adhesive glues, and incisional negative-pressure wound therapy. These devices are designed with the goal of making wound closure more rapid and secure, and decreasing postoperative sequelae. This paper reviews methods available to perform incisional closure and the published clinical data regarding their use.

Experimental study of cavity characteristic induced by vertical water entry impact of a projectile with a 90° cone-shaped head at different velocities

Experimental studies of the vertical water entry of projectile with 90° cone-shaped head were conducted by using high speed camera. The pinch-off types and evolutionary process of the cavity were comprehensively discussed at different water entry impact velocities. The variations of cavitation closure time, water depth at the closure point and length of the warhead cavitation with water entry velocities, as well as the cavitation diameter at different water depth positions were analyzed. The jet phenomenon caused by the closure of the water curtain and contraction-rising process of the cavity near undisturbed free surface were studied, as well as the coupled effect between them. The cavity wall fluctuation occurring after the deep seal was discussed. The results show that with the increase of water entry velocity, the quasi-static closure, shallow closure, deep closure and surface closure of the cavitation occurs respectively, and each closure mode corresponds to a velocity range; the critical water entry velocity of forming cavitation is 0.657 m/s. The diameter of the cavitation presents a nonlinear increase along with the water depth. The initial cavity expansion velocity increases, the maximum diameter of the cavity decreases, the expansion section shortens, the contraction section lengthens, and the acceleration of the expansion and contraction of the cavity increases along with the increase of the water depth at the same time. When the water curtain closes, there will be upward and downward jets, and when the downward jet velocity is relatively large, the projectile motion will be affected. The strength of a water jet induced by longitudinal upward contraction of the cavity near free surface is proportional to the volume of cavity and pinch-off depth. A large strength upward water jet is induced by the coupling of the above all water jet. The longitudinal contraction of the cavity around the projectile and the impact effect of downward jet on projectile would cause the force change of the projectile after deep seal. The fluctuation of the projectile's velocity because of its force change brings the velocity change of fluid and then leads to the fluctuation of the cavity wall. The fluctuation of cavity wall follows the principle of independent expansion of cavitation section.

Water entry of a constraint posture body under different entry angles and ventilation rates

Water entry experiments of a constraint posture projectile were performed under different entry angles and ventilation rates. The near water surface cavity flow characteristics, including splash sheet, surface closure, pull away, deep closure and cavity ripples, were investigated under different entry angles and ventilation rates without the posture perturbation influence of the projectile. The experimental results demonstrate that, the dimensionless cavity surface closure and pull away time increase gradually with the increasing of the water entry angle, and the dimensionless cavity deep closure time and the pinch off depth experience a slight increase and decrease, respectively. The deep closure patterns shift from the point closure to the line closure as the water entry angle increases for the oblique water entry cases. And, the cavity ripples were observed before the pinch off and after the pull away for ours experiment, which are more likely acoustic in origin. In addition, the surface closure contributed by the splash sheet is clearly delayed at similar entry conditions except for the ventilation rate. The dimensionless cavity deep closure times of the ventilation cases are significantly higher than the cases without ventilation. However, with further increase the ventilation, the deep closure time changes slightly.

Barbed Suture Is Associated With Increased Risk of Wound Infection After Unicompartmental Knee Arthroplasty

BackgroundLiterature addressing the risks of barbed suture in arthroplasty remains limited. No study to our knowledge has compared rates of wound infection between barbed and conventional suture after unicompartmental knee arthroplasty (UKA). We hypothesized that barbed suture would be associated with an increased risk of wound infection in patients undergoing UKA. MethodsElectronic records were retrieved for 1040 UKA procedures. Odds ratios with postoperative wound infection as the outcome and barbed suture as the exposure were calculated. Binary logistic regression corrected for age, gender, body mass index, operative time, and risk factors (smoking, diabetes, renal insufficiency, and immunosuppression). Barbed suture consisted of Quill #2 polydioxanone (or #0 Vicryl) for deep closure and Quill 2-0 Monoderm for subcuticular closure. Conventional suture consisted of #0 Vicryl for deep closure and subcuticular 2-0 Monocryl or staples for skin closure. ResultsA total of 839 procedures were included. Barbed suture was used in 333 surgeries, and conventional suture was used in 506. Eight cases of postoperative wound infection were identified. All infections occurred in the barbed suture cohort. Regression analysis revealed an association between subcuticular barbed suture and postoperative wound infection (odds ratio = 22.818, confidence interval = 2.69-2923.91; P = .0074). ConclusionsThe findings indicate that the use of barbed suture in subcuticular layer closure is associated with an increased risk of wound infection. This may be exacerbated by early intensive mobilization, commonly undertaken after UKA to permit rapid functional return. We recommend against the use of barbed suture for subcuticular layer closure in UKA.

An experimental study of water-entry cavitating flows of an end-closed cylindrical shell based on the high-speed imaging technology

The objective of this present study is to address the cavitating flow patterns and regimes in the water-entry cavity. For this purpose, an experimental study of vertical water-entry cavity of an end-closed cylindrical shell is investigated by using high-speed video cameras and visualization technique. According to the cavitating flows as observed in the experiments, two flow pattern forms of fluctuation cavitation and cloud cavitation are found around the body. A further insight into the characteristics of the cavity shape and the variation in the cavity fluctuations parameters is gained by analyzing the image data. Furthermore, the experiments at different impact velocities are conducted to analyze the effects of impact velocity on the flow patterns and parameters. Finally, the formation mechanisms of cavitation fluctuations and cavitation clouds are studied based on the basic theory of fluid mechanics. The obtained results show that the cavitation flow pattern form of fluctuation cavitation occurs under the impact velocity condition of low speed, and the cloud cavitation occurs under the velocity condition of high speed. As fluctuation cavitation, the maximal extension diameters of cavitation fluctuate periodically along the water depth, and the speeds of extension and shrinkage are both proportional to the extension diameter. The collapses are different for the two flow pattern cavitations, i.e., the fluctuation cavitation, which is of deep closure and closed at the trough of wave cavitation more than once, and the cloud cavitation, which falls off and forms the leading edge of the cylindrical shell. The frequency fluctuation is independent of the impact velocity, the corresponding pinch-off time decreases with increasing the impact velocity, and the pinch-off time decreases in a nearly linear relation with Froude number. The water poured to the cylindrical shell causes the internal air to compress and expand, and as a consequence of these effects, periodic disturbances of pressure distribution and velocity field occur around the leading edge of the cylindrical shell, then the extended intensity of the cross section of the cavity shows variation in this process, which can be defined as fluctuation cavitation pattern. It appears that the re-entrant flow after the pinch-off at the trailing edge of cavity, then the laminar-turbulent transition is waken as a consequence of the re-entrant flow moving upstream, which flow pattern involved in this structure occurs as cloud cavitation.

Anterior Cruciate Ligament Reconstruction with Quadriceps Tendon Autograft: A Minimally Invasive Harvest Technique.

We describe a minimally invasive surgical technique for harvest of a quadriceps tendon autograft that reliably produces a graft suitable for anterior cruciate ligament (ACL) reconstruction while minimizing morbidity and complications classically associated with alternative autograft choices. Position the patient supine on the operating room table. Palpate and mark soft-tissue and osseous landmarks on the involved extremity. Perform the incision and subcutaneous dissection. Harvest the graft. Prepare the graft. If a partial-thickness graft is harvested, no deep closure is needed. Since September of 2011, the quadriceps tendon has been our autograft of choice for ACL reconstruction.IndicationsContraindicationsPitfalls & Challenges.

Vertical Water-Entry of Bullet-Shaped Projectiles

The vertical water-entry behavior of bullet-shaped projectiles was experimentally and theoretically studied. Particular attention was given to characterizing projectile dynamics, the resultant evolution of air cavity and particularly surface closure before deep closure in the moderate speed. We developed equations for the projectile motion with significant and negligible gravitational effects. Based on the solution to the Rayleigh-Besant problem, a theoretical model was developed to describe the evolution of the cavity shape, including the time evolution of the cavity on fixed locations and its location evolutions at fixed times. The gravitation effects during the initial stage of the impact of the projectile on the water can be ignored, but those during the later stage should be considered, many literatures do not have the report of this aspect. The theoretical predictions were consistent with the experimental observations. The evolution of air cavity had a significant effect on ballistic stability.