Surge irrigation, an intermittent release of water into furrows is an efficient method of water conservation if the flow and frequency of water delivery are optimized. It increases the advance velocity, causes uniform distribution over the furrows, and reduces deep percolation losses. The objectives of this study were to compare yield indices for surge flow and continuous flow, and to evaluate cycle ratios and suitable input discharge in the study area, and also to determine the difference of advance velocity of the wetting front between surge irrigations and continuous flow irrigations. Seventy meter long furrows, 0.5 and 2 lit/s discharge rates, and various pulse ratios were compared with the constant inflow. Field experiments were conducted including determination of the number of furrows and the number of surges, and continuous flow treatments (2 discharges and various cycle ratios for surge flow). Advance velocity, in-and-out flows, and soil water content prior and after the termination of irrigation were measured at the Khalatpoushan Research Station of the Tabriz University. Then flow parameters and infiltration rate for furrows were simulated using the SIRMOD surface irrigation model for both the surge and constant flows. In order to compare the advance velocity of wetting front for surge and continuous irrigations, the HYDRUS 2-D model was used for simulating the advance of wetting front in the wet soil volume in the furrow. The results of simulation show that the final infiltration rate during surge flow was half of continuous flow for one of the treatments. Advance velocity of wetting front in surge treatments was more than continuous treatments with the same volume of applied water. Overall, the S22 treatment (the inflow of 0.5 lit/s and the pulse ratio of 1:4) had the best performance, and S13 treatment (the inflow of 0.5 lit/s and the pulse ratio 2:3), had the poorest performance, even worse than constant flow treatments.

Determination of fertigation criteria in new surface irrigation methods, especially furrow irrigation through surge flow, is necessary in order to increase water and fertigation use efficiency. Distribution uniformities of the water and nitrate are the most important indicators of the surface irrigation fertigation. For this purpose in this research, water and nitrate distribution uniformity indicators in furrow fertigation with surge and continuous flow regimes were evaluated using field experiments. The study was conducted in a soil with clay loam texture at the experimental station of the College of Agriculture and Natural Resources, University of Tehran in June, 2012. Fertigation management strategies in experiments with surge flow included injecting fertilizer during all advancing cycles, wetting phase and last advancing cycle plus start of wetting phase. Fertilizer injection for continuous flow was applied in the second half of advancing and wetting phases. Low quarter distribution uniformity of the nitrate in experiments with surge and continuous flow amounted to 54.4-93.8% and 77.7-93.6%, respectively. Also, low quarter distribution uniformity of the water for the same experiments amounted to 88.0-93.7% and 78.0-90.5%, respectively. Nitrate losses in all experiments were through runoff and its values in these experiments amounted to 5.1-47.1% and 3.7-27.2%, respectively. Low quarter concept was also used as an index for evaluating the water and nitrate application efficiency and distribution uniformity. The values of these indices for nitrate in experiments with surge and continuous flow regimes were calculated to be 45.0-80.5% and 68.2-79.5%, respectively. Overall, fertilizer injections in all surges and second half of advancing phase, respectively in furrow fertigation with surge and continuous flow regimes stand at the proper management practices for water and fertilizer.

Surge flow irrigation is a new concept in surface irrigation methods that improves preformance efficiency and uniformity in furrow irrigation. Surge flow irrigation is only effective in the first two irrigations. Its effectiveness will be the same as continuous irrigation on the rest. In surge flow irrigation, inflow rate is kept constant. Stepwise inflow rate increment promotes wetted perimeter over which infiltration occurs. The effect of this concept is not yet known on application efficiency and irrigation uniformity. In order to compare advance phase water saving and moisture uniformity, three treatments such as continuous flow, surge flow with constant inflow rate, surge flow with stepwise flow rate were selected. Field experiments for this research were carried out in Agricultural Research Station at University of Tehran located in Karaj. Soil texture in study area is sandy clay loam. Tests were conducted two times for the first irrigation in 150 and 200 m furrows.Results indicated on the first two irrigations, the volume of water required to complete advance phase in surge flow irrigation with stepwise inflow increase, was 10 and 12 percent less, respectively, in compare to surge flow irrigation with constant inflow rate. In the meantime, soil moisture distribution also was more uniform than the surge flow irrigation with constant inflow rate.

Aerodynamic heating and drag reduction in hypersonic flying is one of the most important challenges in this speed range. In decades, the use of the spike method has been considered by the experts as an appropriate tool for aerodynamic drag reduction and a lot of research is done to optimize the geometry, dimensions and type of spike aerodisk. In this study, the effect of spike length on the wave drag reduction of a standard nose, HB1, in hypersonic flow regime was evaluated using two methods of numerical simulation and experimental test of hypersonic wind tunnel in Mach number 6. 4. For this purpose, the amount of drag force applied to the model was investigated in four types of spikes with length to diameter ratios of 0. 5, 1. 0, 1. 5 and 2. 0. The results indicate that the numerical solution has a significant adaptation with experimental results and, according to expectations, Spike has a considerable effect on the nose hypersonic drag reduction. It was also observed that the increase in spike length caused a further decrease in the nose wave drag and the length to diameter ratio of 2 with the drag reduction of 43% has shown the best performance.

Introduction: In recent years, to increase the efficiency of surface irrigation methods, new techniques such as surge irrigation have been developed. Numerous studies have shown that the surge flow can reduce water consumption in the advance phase and subsequently improve irrigation efficiency and water distribution uniformity. One of the factors affecting the performance of surface irrigation systems is the accurate estimation of infiltration. Due to continuous changes in the infiltration process during on-off cycles in surge irrigation, determining the empirical equation of infiltration in surge irrigation method is complex and requires timeconsuming and costly field data. As a result, proper selection and parameterization of empirical equations with a simplified procedure are needed. The goal of this research was the field evaluation of the point method (surge infiltrometer) to simulate the infiltration process in advance phase surges. Materials and Methods: A field experiment was conducted at the experimental station of the College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran. A ring infiltrometer was modified by connecting a pipe arm for inward and outward water flow to the ring and from the ring to the pipe to create onoff surge cycles, respectively. Water entered the ring through the inlet hole at the top of the pipe arm and water depth was recorded at different time intervals during the on-time of each cycle. Four treatments were performed for infiltration tests under surge flow, including different cycle time and ratio. Also, infiltration tests were performed under continuous flow conditions. To simulate the first (dry soil) and second irrigation conditions, infiltration experiments were conducted twice on an 8-day interval. The Kostiakov infiltration equation was corrected by applying surge factors to predict infiltration water depth for subsequent surges, using first surge data. The empirical coefficients of the Kostiakov equation were calculated by applying the two-point technique. Results and Discussion: Results of the study revealed that the infiltration data simulated by the developed Kostiakov equation matched closely with those collected from the surge-ring infiltrometer. The coefficient of determination and the root mean square error were calculated to be 0. 92 to 0. 97 and 0. 03 to 0. 16 cm, respectively. In general, the amount of cumulative infiltration in the second and subsequent surges decreased. The ratio of the infiltration depth at the end of the second to the first surge was less than 0. 5. In all experiments, the depth of water infiltrated in the third surge was significantly reduced and almost reached to the final infiltration rate. As the cycle ratio increased, the cumulative infiltration also increased. However, the effect of on-off time on the infiltrated water depth in the first experiment was greater than that in the second experiment. It was concluded that in the first experiments, the surging phenomena substantially reduced water movement and the reduction in cumulative infiltration ranged from 50 to 70% during the second surge and from 59 to 85% during the third surge. The above values were determined 52 to 76% and 61 to 88% for the second experiment, respectively. A significant difference was observed between surge and continuous flow tests. The surge flow led to a 46 to 76% reduction in the cumulative infiltration depth compared to the continuous flow. The effect of surge flow was greater in the first experiments. Conclusion: One of the most important points in designing surface irrigation systems is to determine the infiltration equation parameters. In particular, the difficulty involved in the planning and design of surge irrigation systems is the prior knowledge and understanding of how infiltration changes occur during surging. The main objective of the present study was to evaluate the surge ring infiltrometer test to predict the infiltration in the second and third surges using the first surge data. The results obtained from the surge infiltrometer experiments showed that the use of surge irrigation has the potential to reduce infiltration. The observed and predicted cumulative infiltration for the second and third surges showed a good agreement. The surge-ring infiltrometer has the potential for creating an on-off mechanism and is best suited to determine the cumulative infiltration from surges for constant on-off time surge intervals.

Numerical study of turbulent and laminar flow is investigated for an incompressible nanofluid flow in a 2D wavy channel by using the finite volume method (FVM). The results of the Nusselt number, pressure drop, and thermal performance has obtained for diameter ratios (a/b=0, 0. 25, 0. 5, 0. 75, 1), volume concentration(FI = 0%, 2%, 4%) and nanoparticle diameters in four Reynolds number(Re=10000, 20000, 30000, 40000). The validation was compared with analytical and numerical studies. The results shown a good convergence between them. The results showed that using wavy parts caused to increasing in heat transfer rate and pressure drop by 1. 78 and 8. 1 times respectively. Additionally, augmentation of the volume concentration increased the heat transfer rate and pressure drop by 2. 1 and 3 times respectively. The use of laminar flow also had a higher heat transfer rate, pressure drop and, thermal performance compared to turbulent flow within the Reynolds 1000 range.

This numerical study carried out to find the effects of wall geometry and fluid content of a sinusoidal corrugated channel of turbulent fluid flow on increasing thermal-hydraulic performance factor. The channel consisted of two zones namely, zone1 where the fluid pass through it, and zone2 where the fluid was trapped in the channel walls. . Air and TiO2-water Nano fluid were used as fluid in 1st and 2nd zones. Nano fluid was homogeneous, single-phase, with volumetric concentration of 1%. The upper and lower plates of the channel were heated with a constant heat flux of 616 W/m2. The Reynolds numbers of fluid flow of channel were 3700 to 40, 000. The turbulent fluid flow in the 1st zone was simulated using the standard k-ε model. The effects of fluid type used inside the channel wall and wave angle and wave height were investigated. The results showed that when the TiO2-water nanofluid was in the 2nd zone and air passed through 1st zone, the channel performance was the best. The optimum wave angle is 35 degrees and produced the most thermal-hydraulic performance factor in 12000 to 40000 Reynolds numbers. With increasing wave height from 4 to 6 mm, the thermal-hydraulic performance coefficient increases from 65 to 110%. The effect of wave height on the increase of the thermal-hydraulic performance coefficient was more significant than the wave angle change.