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In this work, the application of a shear stress transport based-RANS/LES turbulence modelling approach on a fluid-structure interaction (FSI) benchmark is considered after a transient computation of turbulent flow over the configuration on an LES quality mesh is to be performed. Within the unsteady decoupled simulation the scale resolving method successfully produces complex unsteady eddy sizes behind the reference test case. At a subcritical Reynolds number, a numerical Strouhal number of 0.184 which is close to a reference value of 0.18 is demonstrated by the RANS/LES turbulence model. In this scenario, a rubber added on the back part of a fixed circular cylinder is treated as a rigid thin plate during the pure flow simulation. On the LES grid resolution, the shielding function resided in the hybrid limiter of the scale resolving formulation is found to be strong to safeguard the activation of the RANS mode in the near wall region where the demarcation line between the RANS and LES modes uniquely resembles the geometry. Moreover, in the FSI simulation resolved turbulence scales interacting with moving and deforming rubber immersed in the subcritical Reynolds number-turbulent flow are successfully captured by the hybrid modelling technique coupled with a structural solver under the coupling procedure of an implicit partitioned approach. Similar with earlier studies with different scale-resolving proposals on the same FSI case, a periodic oscillating motion of the rubber that is produced from a phase-averaging method is also demonstrated in this present investigation. Nevertheless, a non-physical deformation of the rubber in the spanwise direction occurs. The new FSI result is evaluated with existing results from earlier works as a pivotal basis for further researches, such as implementations of new mesh stiffness model and filter width.

Within the framework of eddy-resolving simulation, this paper aims to study the potential of two advanced turbulence modeling approaches in resolving turbulence scales over a reference geometry. Two k-ω SST based-scale resolving schemes are applied on a circular cylinder with a splitter immersed in turbulent flow at a sub-critical Reynolds number of around 3 × 104. The scale resolving computations starts with RANS predictions using the SST model where spatial and temporal grid studies are to be performed to craft the numerical mesh resolution required. With a standard k-ω SST model the results of the spatial and temporal grid sensitivity studies on the 2D domain give optimum mesh and timestep size to demonstrate the Strouhal number of 0.238 and unsuppressed vortex shedding after the rigid splitter. The vortex shedding phenomenon was also proven in an experimental study with a similar Reynolds number and equivalent ratios of splitter thickness and length to the cylinder diameter of 0.09 and 2.72, respectively. Under the optimum mesh and timestep size, comparison of the Strouhal number on 2D and 3D domains with one of the experiment is also performed, serving as a baseline point to modify the production of turbulent kinetic energy term in the k-transport equation of the standard k-ω SST model in order to evade an excessive generation of the turbulent kinetic energy due to the existence of a stagnation region ahead of the cylinder. On the 3D domain with the numerical ingredients, the computational results obtained with a modified k-ω SST model provide an encouraging result closer to the experimental data, giving the Strouhal number of 0.234. To study the inherent strategies in the two vorticity resolving schemes, the highest levels of the spatial and temporal grids are used. This is crucial to detect whether or not the finest mesh is prone to a numerical problem in one of the scale resolving formulations. During this stage, the ratio of the grid length scale to the RANS integral length scale, which is the functions of the turbulent kinetic energy and dissipation, in critical regions is scrutinized to be less than 0.1 – 0.2 to maintain high-quality mesh. The numerical results from the modified k-ω SST based-hybrid RANS-LES proposals suggest a prospective approach based on the modification of the dissipation term in the k-transport equation to be used even with a coarser grid, which is able to resolve turbulence scales on the configuration. The Strouhal number of 0.189 predicted by the superior model is close to a reference value in the experiment. The weakness and strategy in each scale resolving scheme are discussed within the context of crucial issues in the progress of the non-zonal hybrid RANS-LES models.

The concept of physics can be applied to aspects of customs and culture in order to preserve local wisdom. One way to introduce the customs and culture of the local area can be done by studying traditional houses. The foundation structure of the Jambi’s traditional house uses wooden poles arranged to support the weight above where. Mass of each pole has a correlation with the amount of load that has been distributed evenly. The purpose of this study is to analyse and explain the application of physics concepts in the foundation structure of traditional Jambi houses and to build character education to new generation. The process of collecting data is done by interview, observation, and documentation. The results of interview section are about the advantage of using wood, philosophy and meaning of foundation structure. Based on the data analysis of observation, it is shown that the mass of each pole is strong enough to support the live and dead load that has been analysed. Because it has a pole mass greater than the distributed load. So this can educate the new generation to know the process of making foundation structures with certain calculations that can be analysed through physics concept.

Most of the studies land subsidence and impact have been done on the north coastal area of Java, especially Semarang and Demak. This landsubsidence has a very serious impact both in the infra structure, the economy and the environment. Techniques of observing landsubsidence using geodetic methods have been widely practiced. Geodetic technology is undergoing rapid development, especially in GNSS navigation satellite technology as well as satellite radar interferometry. Both have advantages and disadvantages of each. In this study will examine the application of DinSAR interferometric techniques and GNSS technology to predict the rate of land subsidence coastal of Demak regency. This paper also emphasize the role of GNSS and DinSAR application in deformation especially for landsubsidence monitoring.

One of the challenges in modern computational engineering is the simulation of fluid-structure interaction (FSI) phenomena where one of the crucial issues in the multi-physics simulation is the choice of stiffness model for mesh deformation. This paper focuses on the application of iteratively implicit coupling procedure on two transient FSI cases of vortex induced-vibration (VIV) that manifest oscillating flexible structures. The aim is to study various mesh stiffness models in the Laplace equation of diffusion employed within the arbitrary Lagrangian-Eulerian (ALE) methodology to handle the moving mesh. In the first case where a laminar flow interacted with a flexible splitter, it was demonstrated that a near FSI boundaries increased-stiffness model prevails to manage a large deformation of the moving structure as compared to a near volume increased-stiffness model. However, the potential technique could not be exploited to the second FSI configuration, where the effect of the turbulence of flow was included. It was found that the mesh topology near the FSI interface was collapsed. Instead of utilizing the same approach, a mesh stiffness based on a wall distance was found to be auspicious. Thus, the mesh stiffness model in the FSI simulation is case-dependent.

Turbulence simulation remains one of the active research activities in computational engineering. Along with the increase in computing power and the prime motivation of improving the accuracy of statistical turbulence modeling approaches and reducing the expensive computational cost of both direct numerical and large turbulence scale- resolving simulations, various hybrid turbulence models being capable of capturing unsteadiness in the turbulence are now accessible. Nevertheless this introduces the daunting task to select an appropriate method for different cases as one can not know a priori the inherent nature of the turbulence. It is the aim of this paper to address recent progresses and further researches within a branch of the hybrid RANS-LES models examined by the first author as simple test cases but generating complex turbulent flows are available from experimentation. In particular, failure of a seamless hybrid formulation not explicitly dependent on the grid scale is discussed. From the literature, it is practical that at least one can go on with confidence when choosing a potential hybrid model by intuitively distinguishing between strongly and weakly unstable turbulent flows.

In this paper, statistical quantities of a fully pulsed round jet along the jet centerline are reported. A range of the Reynolds (1.5 x 104 < Re < 4 x 104) and Strouhal (0.0064 < St < 0.0076) numbers is used to generate the jet. Physically this unsteady jet produces a series of distinct pulses due to the excitations. The mechanically excitations lead to the appearance of pulse dominated and high turbulence steady jet region in which their existence is of a strong dependence on the level of the controlled parameters. After the pulse merging completes the pulsed jet alters to a self-preserving steady jet with a significantly higher turbulence intensity. Under a constant mass flow rate the pulsed jet tends to be more fluctuating at a less intense pulsation thus permitting the endurance of the normalized periodic component and a more rapid velocity decay in the pulse-dominated region.

This research concerns on the axial measurement of a pulsed-axisymmetric jet to investigate the decay of inverse of mean centerline axial velocity with the use of a single normal hot-wire anemometer. The measurement is performed by controlling mean exit velocity and pulsing frequency. The axial measurement reveals that the pulsation method leads to the appearances of two distinct regions namely the pulsed dominated-and the high turbulence steady jet-regions. However, the existence of the two regions can be controlled by adjusting the mean exit velocity and pulsing frequency. At a high mean exit velocity and low pulsing frequency, the high turbulence steady region is not seen, hence the transition region can not be found. Furthermore, at a high pulsing frequency and a constant mean exit velocity, the pulse dominated region becomes shorter. The present study has provided a comprehensive knowledge in that the trend of the decay rate is very clear under the wide range of pulsation method imposed on the jet. This inclusive understanding becomes a substantial consideration for mixing processes as well as can be used to verify the k-e turbulence model to predict the decay of normalized mean centerline-axial velocity.

This paper reports the statistical accuracy evaluation of the implementation of ensemble-averaged equation used for the measurement of turbulence quantities in a fully pulsed, axisymmetric-subsonic air jet issuing into the still surrounding air. A constant mass flow rate and frequency of pulsation were used to generate the intermittent free jet, which physically contained a period of no flow between pulses due to a mechanical excitation. Time-history records of the random process were gained from a single normal hot-wire probe by a digital sampling technique, where the probe was operated in a constant temperature mode and placed at a fixed location in the jet field with the probe stems parallel to the mean flow direction. Within the framework of amplitude-domain analysis, the accuracy assessment was performed to which the uncertainties of mean value and higher-order moments were evaluated from the given values of sampling parameters, where the estimate of integral-time scale of the random process was the basis for determining the given sampling parameters. The present results suggest appropriate values of number of samples, sampling frequency, and sampling time of the hot-wire anemometer (HWA) technique for a repeatable turbulence measurement in the unsteady jet within a high degree of accuracy.

Experimental results of a fully pulsed subsonic air jet issuing into the still surrounding air are reported in this paper. The intermittent flow containing a period of no flow between pulses due to the mechanically excitation was gauged by a single wire hot-wire anemometer operated in a constant temperature mode. A range of the Reynolds and Strouhal numbers of 1 × 104 < Re < 4 × 104 and 0.0064 < St < 0.0076 respectively was used to define the jets. Results of the traverse measurement agreed with earlier findings demonstrating strong effects of the excitation on the radial profiles of the mean axial velocity of the jet. Within the parameter ranges investigated, the pulsed jets were found to be significantly more spreading than steady jets. A less dispersive pulsed jet, however, appeared at a higher jet exit velocity. Strikingly, contradictory trends in the jet growth and entrainment at the higher and lower Reynolds number were seen as the lower Reynolds number does not produce a widening radial profile as a result of the increasing Strouhal number. From the axial measurements, the pulsed jets were characterized by the pulsed dominated- and high turbulence steady jet region in which their existences heavily relied on the magnitudes of the controlled parameters. A less fluctuating pulsed jet associated with the reduced magnitudes of aggregate turbulence intensity and relative turbulence energy however, appeared at an increased Strouhal number. Comparative studies with the existing results of non-circular orifice jets i.e cruciform, elliptic, and triangular jets are also reported to display the decay rates of centerline axial velocity and the spreading rates of the jets which benefit for the practical purposes.

Radial distribution of the first and higher moments of instantaneous axial velocity of a fully pulsed round jet were investigated along 80 diameters downstream from the jet exit. Response of the unsteady flow to the varying Reynolds and Strouhal numbers thus allowing a series of distinct pulses were sampled using a single wire hot-wire anemometer. It was found that the first moments, as compared to steady jet phenomena, do not maintain self-similarities over the flow domain but their shapes remain unchanged. At a lower Reynolds and Strouhal number, widening radial profiles of the first moment are obtained. Transverse profiles of the third and fourth turbulence moments explain the nature of random process in the mechanically excited jet. Their values were found to remarkably depart from the Gaussian values and to be significantly higher than those of the steady jet across the observed jet widths hence yielding more intense-highly irregular motions and more spreading jet. For all the tested cases, it was demonstrated that the direct effects of the controlled parameters on the flow field become stronger in the outer region than in the inner conterpart of the jet width.

The authors describe two Indonesian siblings affected by a hitherto undocumented form of metaphyseal dysplasia that simulates enchondromatosis. The notable clinical features were short stature and lateral bowing of the lower extremities. These features were readily recognizable at birth. The radiographic examinations showed that the metaphyseal anomalies were localized predominantly in the lower extremities, the hip joints being the most severely affected. The upper extremities showed only minimal abnormalities. The name "Indonesian type of metaphyseal dysplasia" is suggested for this autosomal recessive bone disorder.