Application Of Smoothed Particle Hydrodynamics Modelling to Turbulent Open Channel Flows Over Rough Beds

In this study, 2D and 3D numerical models based on the Smoothed Particle Hydrodynamics (SPH) approach have been developed to simulate turbulent open channel flows over a fixed rough bed. Both models were then used to simulate free surface turbulent flow over a rough boundary, including the free surface dynamic behaviour. The numerical code is based on the open source code SPHysics (http://www.sphysics.org) and during this study significant improvements have been made to this code on the modelling of turbulence and rough bed treatment. A modified sub-particle-scale (SPS) eddy viscosity model is proposed to reflect the turbulence transfer mechanisms and drag force equations are included into the momentum equations to account for the existence of roughness elements on the bed and on sidewalls. The computed results of flow velocity, shear stress and free surface elevations have been compared with detailed laboratory measurements under different flow conditions. The comparison has demonstrated that the modified SPH models can accurately simulate the free surface flows over a fixed rough bed. It was found that the modified 3D model is more accurate than the modified 2D model in predicting the flow velocity, shear stress profiles and the dynamic behaviour of the free surface. The capabilities and limitations of each model to simulate such free surface flow are highlighted and discussed

3D SPH simulation of dynamic water surface and its interaction with underlying flow structure for turbulent open channel flows over rough beds

In this study, a fully 3D numerical model based on the Smoothed Particle Hydrodynamics (SPH) approach has been developed to simulate turbulent open channel flows over a fixed rough bed. The model focuses on the study of dynamic free surface behavior as well as its interaction with underlying flow structures near the rough bed. The model is improved from the open source code SPHysics (http://www.sphysics.org) by adding more advanced turbulence and rough bed treatment schemes. A modified sub-particle-scale (SPS) eddy viscosity model is proposed to reflect the turbulence transfer mechanisms and a modified drag force equation is included into the momentum equations to account for the existence of roughness elements on the bed as well as on the sidewalls. The computed results of various free surface patterns have been compared with the laboratory measurements of the fluctuating water surface elevations in the streamwise and spanwise directions of a rectangular open-channel flow under a range of flow conditions. The comparison has demonstrated that the proposed 3D SPH model can simulate well the complex free surface flows over a fixed rough bed

Sustainability of the Dujiangyan irrigation system for over 2000 years–A numerical investigation of the water and sediment dynamic diversions

The Dujiangyan Irrigation System (DIS), located in the western portion of the Chengdu Plain at the transitional junction between the Qinghai-Tibet Plateau and Sichuan Basin, has been in operation for about 2300 years. The system automatically uses natural topographical and hydrological features and provides automatic water diversion, sediment drainage and intake flow discharge control, thus preventing disastrous events in the region in a ‘natural’ way. Using a numerical modeling approach, this study aims to investigate the reasons behind this natural behavior of the system and provide a better understanding of the complex mechanisms which have caused the sustainability of the DIS for over two millennia. For this purpose, a two-phase flow model based on the Shallow Water Equations (SWEs) is developed to simulate the fluid and sediment motions in the DIS. A coupled explicit-implicit technique based on the Finite Element Method is applied for the fluid flow and a Sediment Mass (SM) model in the framework of the Lagrangian particle method is proposed to simulate the sediment motion under different flow discharge conditions. The results show how different components of the DIS make full use of the hydrodynamic and topographical characteristics of the river to effectively discharge sediment and excess flood to the downstream and create an environmentally sustainable irrigation system

The George Eliot Fellowship- 19

When I wrote the last newsletter we had not then had Gabriel Woolf’s prgramme of readings entitled “The Warwichshire Pen”. It was, as always, immensely successful- in its ccontent, its performance (see the Review, p. 50) and also financially. That we make a profit at all is entirely due to the great generosity of those members who sponsor the two performance each year. Without these good friends we would certainly not be able to play at the University of Warwick Arts Centre and we are so grateful for their help and support. “The Warwichshire Pen” is to be repeated in the county on October 8th. When the National Trust is to present it, with Gabriel Woolf, of course, at Coughton Court, near Alcester, and a N.T. leaflet is enclosed for those members within reach. You will see that Gabriel will be presenting another of his recitals (poetry and songs from World War 1) on October 1st. at Berrington Hall, near Leominster. Next year\u27s programme has already been commissioned for April 27th. and 28th.. As this will be Gabriel\u27s 20th. visit to Warwickshire on our behalf, we have invited him to choose his own anthology of poetry and prose in a programme to be called \u27With Great Pleasure\u27…..and we know his pleasure will include a substantial helping of George Eliot. In the next newsletter, I shall be asking for sponsorship again, so if you have some money you don\u27t know what to do with………! Another event which happened after the preparation of the last newsletter was the Seminar of the Alliance of Literary Societies. This, too, was a great success and MS paved the way for the informal Alliance instigated 15 years ago by the George Eliot Fellowship to become a more formal and, we hope, powerful organisation in protecting our literary heritage and being of mutual benefit to the many literary societies who have become members. The Nuneaton Wreath-laying on June 12th. was well supported and we heard John Burton, Chairmanof the Bedworth Society and a very good friend of the Fellowship, appeal for some restraint in the promotion of tourism. Tourists at any price must be avoided if quality and integrity are to be maintained. John\u27s speech will be published in the 1989 Review. We had two guests of honour at the Westminster Abbey Wreath-laying on June 18th. Our principal guest was Jennifer Uglow whose excellent George Eliot was published in the Virago Pioneers series last year. Also in the Abbey was Mrs. Mary Haight, whose husband, Dr. Gordon Haight, had unveiled the memorial stone eight years earlier. Mrs. Uglow very generously offered Mrs. Haight the pleasure of actually placing the chaplet of laurel and white carnations onto the stone; Mrs. Haight was clearly touched by this warm gesture. By an amazing coincidence, Mrs. Uglow had chosen to speak on the very passage also chosen as her reading by Margaret Wolfit! Something similar happened last year; there must be something about Westminster Abbey! Mrs. Uglow\u27s Address will also appear in the 1989 Review

Closing the Nuclear Fuel Cycle with a Simplified Minor Actinide Lanthanide Separation Process (ALSEP) and Additive Manufacturing

Expanded low-carbon baseload power production through the use of nuclear fission can be enabled by recycling long-lived actinide isotopes within the nuclear fuel cycle. This approach provides the benefits of (a) more completely utilizing the energy potential of mined uranium, (b) reducing the footprint of nuclear geological repositories, and (c) reducing the time required for the radiotoxicity of the disposed waste to decrease to the level of uranium ore from one hundred thousand years to a few hundred years. A key step in achieving this goal is the separation of long-lived isotopes of americium (Am) and curium (Cm) for recycle into fast reactors. To achieve this goal, a novel process was successfully demonstrated on a laboratory scale using a bank of 1.25-cm centrifugal contactors, fabricated by additive manufacturing, and a simulant containing the major fission product elements. Americium and Cm were separated from the lanthanides with over 99.9% completion. The sum of the impurities of the Am/Cm product stream using the simulated raffinate was found to be 3.2 × 10−3 g/L. The process performance was validated using a genuine high burnup used nuclear fuel raffinate in a batch regime. Separation factors of nearly 100 for 154Eu over 241Am were achieved. All these results indicate the process scalability to an engineering scale

SPHysics simulation of laboratory shallow free surface turbulent flows over a rough bed

In this paper, the Smoothed Particle Hydrodynamics method is used to simulate experimental shallow free surface turbulent flows over a rough bed made of regularly packed uniform spheres. The numerical program is based on the open source code SPHysics and significant improvement is made in the turbulence modelling and rough bed treatment within the code. A modified Sub-Particle-Scale eddy viscosity model is proposed to simulate the effect of turbulence transfer mechanisms in the highly-sheared free surface flow, and a drag force term is introduced into the momentum equation as a source term to account for the existence of the bed roughness. To validate the numerical model, a laboratory experiment is carried out to study shallow, turbulent flow behaviour under different flow conditions. The SPH simulations are then compared with the flow velocity, shear stress and turbulent intensity profiles measured via acoustic doppler velocimeters. Several issues with regard to the rough bed hydraulics are investigated, including the study of water surface behaviour and its interaction with the bulk flow

Three-dimensional smoothed particle hydrodynamics modeling of near-shore current flows over rough topographic surface

In this study, a three-dimensional (3D) numerical model based on the smoothed particle hydrodynamics (SPH) approach was developed to simulate the near-shore current flows over a rough topographic surface in the coastal area, where the flows are shallow and demonstrate strong turbulent characteristics. The numerical program is based on the open-source code SPHysics (http://www.sphysics.org), and two major improvements are made to treat the turbulence and rough boundary effects: A modified sub-particle-scale (SPS) eddy viscosity model is developed to address the turbulence transfer of flows, and a drag force equation is included in the momentum equations to account for the influence of roughness element on the bed and lateral boundaries. The computed results of flow velocity, shear stress, and free surface characteristics are compared with the laboratory measurements for a variety of test conditions. It has shown that the present SPH model can accurately simulate 3D-free surface near-shore current flows over a realistic topography with roughness

THE SFR– M * RELATION AND EMPIRICAL STAR FORMATION HISTORIES FROM ZFOURGE AT 0.5 < z < 4

We explore star formation histories (SFHs) of galaxies based on the evolution of the star formation rate stellar mass relation (SFR-M∗). Using data from the FourStar Galaxy Evolution Survey (ZFOURGE) in combination with far-IR imaging from the Spitzer and Herschel observatories we measure the SFR-M∗ relation at 0.5 &lt; z &lt; 4. Similar to recent works we find that the average infrared spectral energy distributions of galaxies are roughly consistent with a single infrared template across a broad range of redshifts and stellar masses, with evidence for only weak deviations. We find that the SFR-M∗ relation is not consistent with a single power law of the form at any redshift; it has a power law slope of α ∼ 1 at low masses, and becomes shallower above a turnover mass (M0) that ranges from 109.5 to 1010.8 M⊙, with evidence that M0 increases with redshift. We compare our measurements to results from state-of-the-art cosmological simulations, and find general agreement in the slope of the SFR-M∗ relation albeit with systematic offsets. We use the evolving SFR-M∗ sequence to generate SFHs, finding that typical SFRs of individual galaxies rise at early times and decline after reaching a peak. This peak occurs earlier for more massive galaxies. We integrate these SFHs to generate mass growth histories and compare to the implied mass growth from the evolution of the stellar mass function (SMF). We find that these two estimates are in broad qualitative agreement, but that there is room for improvement at a more detailed level. At early times the SFHs suggest mass growth rates that are as much as 10× higher than inferred from the SMF. However, at later times the SFHs under-predict the inferred evolution, as is expected in the case of additional growth due to mergers

The large area detector onboard the eXTP mission

The Large Area Detector (LAD) is the high-throughput, spectral-timing instrument onboard the eXTP mission, a flagship mission of the Chinese Academy of Sciences and the China National Space Administration, with a large European participation coordinated by Italy and Spain. The eXTP mission is currently performing its phase B study, with a target launch at the end-2027. The eXTP scientific payload includes four instruments (SFA, PFA, LAD and WFM) offering unprecedented simultaneous wide-band X-ray timing and polarimetry sensitivity. The LAD instrument is based on the design originally proposed for the LOFT mission. It envisages a deployed 3.2 m2 effective area in the 2-30 keV energy range, achieved through the technology of the large-area Silicon Drift Detectors - offering a spectral resolution of up to 200 eV FWHM at 6 keV - and of capillary plate collimators - limiting the field of view to about 1 degree. In this paper we will provide an overview of the LAD instrument design, its current status of development and anticipated performance

Pengembangan Sistem Penyimpanan Data Berbasis MONGODB Dan GRIDFS Untuk Menyimpan Data Yang Beragam Dari Node Sensor

Internet of things memegang peranan penting dalam perkembangan internet saat ini. Implementasi dari IoT menghasilkan berbagai data yang heterogen dari sensor, dan akan berkembang semakin besar. Contoh dari heterogen adalah data temperature, kelembapan, dan gambar yang berupa file. Hal tersebut menjadi kendala dalam pemilihan metode pada media penyimpanan. Dari permasalahan ini, solusi yang paling mungkin diterapkan adalah penerapan metode NoSQL. Oleh karena itu, pada penelitian ini diusulkan sebuah media penyimpanan berbasis MongoDB dan GridFS yang merupakan database NoSQL untuk menjawab tantangan tersebut. Penelitian ini juga mengusulkan sebuah Internet Gateway Device untuk menghubungkan middleware yang telah ada dengan pusat data. Solusi tersebut dibungkus dalam sebuah framework yang didalamnya terdapat sebuah web service untuk memudahkan proses request dan response. Pengujian kinerja sistem dilakukan dari segi fungsional, skalabilitas, serta response time penyimpanan dan pengambilan data. Hasil dari pengujian fungsional didapatkan bahwa sistem penyimpanan data yang dikembangkan sudah berjalan sesuai dengan fungsinya dalam menyimpan beragam data ke dalam MongoDB dan GridFS. Pada pengujian skalabilitas web service, menghasilkan rata-rata 173,66 request fungsi GET, dan 433,33 untuk request fungsi POST. Aspek lain yang diuji ialah response time dalam menampilkan data pada IoT Apps yang diambil dari data storage, untuk pengujian sebanyak 50 data menghasilkan response time 0,186 detik untuk MongoDB dan 0,185 untuk GridFS. Berdasarkan hasil tersebut, sistem ini dapat menjadi solusi dari permasalahan penyimpanan data IoT