boundary condition

The observed damage during the past earthquakes shows that the damage of the masonry infill in the in-plane and the reduction of the contact surface between the masonry infill and the surrounding frame led to an increase in the vulnerability out-of-plane. Considering the different contact conditions of the masonry infill with the surrounding concrete frame, the interaction, and influence of the out-of-plane on the in-plane behavior of the masonry infills, which is a new topic in the field of seismic performance of the masonry infills. In this paper, the effect of different boundary conditions the masonry infill and the reinforced concrete frame, which include four edges supported by the frame, three edges supported by the frame, two horizontal edges supported by the frame, and one edge supported by the frame, by analyzing three types of loading, which are: 1-out-of-plane loading only, 2-the out-of-plane loading after in-plane loading, 3-the in-plane loading after out-of-plane loading, have been evaluated by using the finite element software ABAQUS. The results demonstrated that the absence of proper connection between the frame structure and the infill increases the Out-of-plane direction vulnerability, and does not prevent their collapse. Previous damage due to in-plane loading, which reached a maximum drift of 3%, can reduce about 70% of the out-of-plane capacity of the infill frame and consequently, the strength and stiffness were affected by the boundary conditions and type loading.

Lattice Boltzmann method is one of computational fluid dynamic subdivisions. Despite complicated mathematics involved in its background, end simple relations dominate on it; so in comparison to the conventional computational fluid dynamic methods, simpler computer programs are needed. Due to its characteristics for parallel programming, this method is considered efficient for the simulation of complex geometry flows, in which a large amount of computational memories is needed. Because of the curved boundaries in the complex geometries, detecting the proper curved boundary condition is unavoidable for the lattice Boltzmann method. For this purpose, more works have been done, and different curved boundary conditions have been proposed. At the present work, first, some curved boundary conditions have been reviewed; then a simplified curved boundary condition is proposed. A computer program based on the lattice Boltzmann method, in FORTRAN language, has been prepared; in this program, the boundary condition along with some others applied on it is proposed. To verify the accuracy and correctness of the proposed boundary condition, 2D cavity flow has been simulated and compared to the available numerical results. Adaptation of the achieved results with those of previous researchers verifies the prepared program correctness. Also, two fluid flows have been simulated, a flow around a stationary cylinder in a 2D channel and one between two stationary and moving cylinders. The results of simulations with the proposed boundary condition, along with the previous boundary conditions, have been compared to the available results. Comparisons demonstrate that solutions with proper accuracy could be obtained by the proposed boundary condition.

The leakage losses from the unlined canals are a major contributor to water losses in the agricultural sector. An understanding of the nature of leakage losses can help to improved water conveyance efficiency and provides solutions to solving water scarcity problems. In this research, numerical simulation was used to study the effective factors on seepage from earth canals. To verify the available information, some of the earthen canals in Zayandehrud irrigation network were used. A number of 246 numerical models including different sections of trapezoidal, rectangular and triangular earthen canals were performed using SEEP/W software. The results showed that, for numerical simulation a width of 15 times the width of the water surface in the canal would be required for the modelling of the left and right lateral boundaries. The comparison of seepage with empirical relationships showed that the empirical relationships show a large error in the seepage estimation, although Moritz's relation with the coefficient of determination 0.373 was better than the rest. Linear and nonlinear multivariate regression relationships provide a suitable match for seepage discharge estimation. Linear relationship was preferable due to small root mean square error (RMSE) and its simplicity. Wetted perimeter has been distinguished effective parameter in seepage from canal, but canal side slope had low effect on seepage. It is suggested that in future studies, the effect of groundwater depth on leakage from the canal should be considered.

Wave run up and overtopping are two important processes in design of coastal structures and in definition of their crest elevation. Wave run up in contribution with wave breaking generates local turbulences as well as large deformations around free surface profile. Smoothed Particle Hydrodynamic (SPH) method as a powerful Lagrangian method in modeling free surface flows is modified and applied in this study to estimate wave run up properly. Two modifications i.e. stepped and smoothed approaches are introduced to implement bed shear stress in SPH models. The results are compared with reliable predictions based on experimental and analytical studies. It is concluded that neglecting bed shear stress as a common practice in SPH methods can generate significant errors in estimating wave run up, while these errors are diminished efficiently by means of the introduced methods. The rate of this improvement, however, depends on slope geometry as well as wave condition and it is more sensible in simulating sliding waves over the bed slope during run up phenomenon. In this case, 90% error of the unmodified methods has been decreased to 6% using the modified SPH method. In addition, parallel processing using graphical processing units (GPU) are utilized to increase the efficiency of the modified model. The efficiency of GPU in comparison with CPU is evaluated and computational costs of different numerical steps are analyzed. It is observed that calculation of forces is the main time consuming step and using GPU can speed up the modified model significantly.

In this study, effects of various boundary conditions on the free vibration of double layer graphene nanoribbons (DLGNRs) are investigated by considering both of tensile-compressive and shear effects of van der Waals (vdWs) interactions. Sandwich beam theory is used to model the DLGNRs. In the references, only one of tensile-compressive or shear effects of vdWs interactions have been considered. Based on sandwich beams theory, vdWs interactions are equivalent to the sandwich core and are modeled in a way that they can withstand the tensile-compressive and shear forces simultaneously. Hamilton’s principle is employed to extract governing equations of motion and boundary conditions. Harmonic differential quadrature method is utilized to investigate natural frequencies and related mode shapes of DLGNRs. In order to verify, results are compared to other literatures in a condition that one of the vdWs effects to be neglected. The effect of boundary condition and interlayer shear direction on the mode shape, sequence and value of DLGNRs natural frequencies are investigated.

The historical application of tie rods in historical buildings was used in the past to ensure the stability of arches and vaults against gravity and horizontal loads. Therefore, the necessity of tie rod health monitoring is a prevalent subject in the vulnerability assessment of historical buildings. The main purpose of this research is to evaluate the dynamic characteristics of tie rods. Also, the eect of several parameters, such as known and unknown boundary conditions, length and cross section, exural stiness and axial load, on fundamental frequency, has been evaluated. As a result, after a series of analytical modeling, practical graphs for three types of beam end connection have been developed. It is possible to calculate axial force with the fundamental frequency of in-situ testing with the proposed graphs. Results showed that the frequency is sensitive to all the aforementioned factors. For instance, under known boundary condition, the eect of the support type is more tangible for long span beams. Also, under constant tensile stress, changes in the boundary condition of tie rods with small cross sections did not aect the frequency considerably. Furthermore, length factors for a pinned-pinned beam with small tensile force are not sensitive in comparison with other support conditions. Comparison of analytical results of axial load and exural stiness with experimental data of reference 1, showed an acceptable conformity between them. The maximum error for tensile stress was calculated as 12%. This error was 5% for compressive stress. Furthermore, analytical exural stiness approached a full rigid support condition, while tensile force increased. This is due to the geometric eect of tensile force on the stiness matrix of the beam. Also, for unknown boundary conditions, estimated buckling force, regarding Newmark's analytical formulation, had 3.1% error, with the corresponding force from in-situ dynamic testing obtained from reference 1.

This paper evaluates the efficiency of using surface water simulation results to improve the accuracy of groundwater simulation due to improving the accuracy of its input boundary conditions. The three most important data sets of boundary conditions in groundwater flow simulation are groundwater recharge، evapotranspiration rates and their regional distributions that little information is usually available about them. Moreover، the incorrect definition of these values can lead to uncertain groundwater modeling that is not applicable for groundwater resources management. In the most of previous studies done in Iran، percentage of the average regional precipitation and the local pan evaporation data (available from local weather stations) are used as the regional groundwater recharge and evapotranspiration rates، respectively but they have high uncertainty in their quantities and spatial distributions. In this research in order to solve this problem، the values of groundwater recharge and evapotranspiration rates and their regional distributions، obtained from SWAT modeling results، were used as the related input boundary conditions data in groundwater flow simulation using MODFLOW model. SWAT model is a comprehensive watershed model that calculates these values in each Hydrologic Response Unit (HRU). The study aquifer in this research was Silakhor shallow aquifer with the area of 590 km2 located in Lorestan province of Iran. The annual water table depth in different locations of this aquifer had been reported from 0. 75 to 40 meter. Using this approach for improving boundary conditions in groundwater simulation and its evaluation was carried out for first time in Iran. The SWAT model was run for a period of 7 years from 2002 to 2008. After calibration and verification of the model using hydrodynamic data of Silakhor and Tire-Doroud gauging stations، the values of groundwater recharge and evapotranspiration rates in each HRU were extracted. The MODFLOW model was run for the period of 9 months of 2009 using these simulated boundary conditions and the other required information. For comparison of the calculated values with the observed values of water table depths in the 20 piezometers for the period of 9 months of 2009، the Root Mean Square Error (RMSE) and Mean Absolute Errors (MAE) were obtained 1m and less than 1m، respectively. In continuous of this research، the values of 5، 10 and 15 percent of regional average precipitation and the evaporation data in Silakhor pan evaporation gauging station were used as usual boundary condition for groundwater simulation using the MODFLOW model. For comparison of the simulated values of water tables depths obtained from this usual approach with the observed ones، the both of RMSE and MAE values were calculated more than 1 meter. Therefore this research showed that using integrated SWAT-MODFLOW models was more applicable in the groundwater simulation in the study aquifer.

I n t h i s p a p e r, a S m o o t h e d P a r t i c l e H y d r o d y n a m i c s m e t h o d i s i n t r o d u c e d t o s i m u l a t e p a r t i c u l a t e f l o w p r o b l e m s s e e n i n, f o r e x a m p l e, b i o l o g i c a l o r r e f i n e r y i n d u s t r i e s. T o t h i s e n d, t h e c a p a b i l i t y o f t h e S m o o t h e d P a r t i c l e H y d r o d y n a m i c s m e t h o d h a s b e e n i m p r o v e d u s i n g a n e w s o l i d b o u n d a r y t r e a t m e n t m e t h o d, a l o n g w i t h t h e s o-c a l l e d r e n o r m a l i z e d s p a t i a l d e r i v a t i v e s c h e m e s. I n t h i s m e t h o d, a s u f f i c i e n t l y a c c u r a t e p r e s s u r e i s o b t a i n e d a t t h e s o l i d s u r f a c e u s i n g t h e f l u i d e q u a t i o n o f m o t i o n. A s a r e s u l t o f t h i s, t h e f l u i d-s o l i d i n t e r a c t i o n f o r c e s c a n b e e f f i c i e n t l y c a l c u l a t e d.I n o r d e r t o a l l e v i a t e t h e p r o b l e m s c a u s e d b y d e f i c i e n c i e s i n t h e S P H p a r t i c l e d i s t r i b u t i o n i n t h e n e i g h b o r h o o d o f t h e s o l i d s u r f a c e s, r e n o r m a l i z e d s c h e m e s a r e a c q u i r e d f o r t h e f i r s t a n d s e c o n d o r d e r s p a t i a l d e r i v a t i v e s. T h e s e s c h e m e s l e a d t o a c o n s i s t e n t m e t h o d a n d f a c i l i t a t e t h e i m p l e m e n t a t i o n o f t h e p r o p o s e d s o l i d b o u n d a r y t r e a t m e n t m e t h o d.U s i n g a w e a k l y c o m p r e s s i b l e S P H s c h e m e c a n p o t e n t i a l l y l e a d t o s e v e r e p r e s s u r e o s c i l l a t i o n s t h a t e v e n t u a l l y c a u s e a f a i l u r e i n t h e s o l u t i o n p r o c e d u r e. H e r e,t h e s p u r i o u s p r e s s u r e o s c i l l a t i o n s a r e r e d u c e d b y u s i n g a m o d i f i e d c o n t i n u i t y e q u a t i o n, i n w h i c h t h e f i r s t a n d s e c o n d o r d e r d e r i v a t i o n s o f t h e p r e s s u r e f i e l d a r e t a k e n i n t o a c c o u n t.T h e p r o p o s e d m e t h o d i s v e r i f i e d b y c o m p a r i n g t h e r e s u l t s o f t h e s i m u l a t i o n s o f f a l l i n g c i r c u l a r c y l i n d e r s w i t h t h e a v a i l a b l e d a t a, i n a t w o-d i m e n s i o n a l c l o s e d c h a n n e l, f i l l e d w i t h a n i n c o m p r e s s i b l e N e w t o n i a n f l u i d. T h e f a l l i n g o f a s i n g l e s o l i d b o d y c o m e s a s t h e f i r s t b e n c h m a r k p r o b l e m i n t h e c o n t e x t o f p a r t i c u l a t e f l o w s. I t i s s h o w n t h a t t h e r e s u l t h a s g o o d a g r e e m e n t w i t h t h o s e p r e v i o u s l y r e p o r t e d, w h i l e i t i s i n d e p e n d e n t f r o m t h e r e s o l u t i o n o f t h e d o m a i n d i s c r e t i z a t i o n. I n t h e s e c o n d b e n c h m a r k, t h e s o-c a l l e d d r a f t i n g-k i s s i n g a n d t u m b l i n g o f t w o f a l l i n g c y l i n d e r s i s s i m u l a t e d. T h e s o l i d-s o l i d c o l l i s i o n i s t r e a t e d b y u s i n g a s i m p l e r e p u l s i v e f o r c e. G o o d a g r e e m e n t w i t h t h e a v a i l a b l e d a t a i s a c h i e v e d. T h e l a s t s i m u l a t i o n i n t h i s p a p e r s h o w s t h e r e s u l t i n g d e v i a t i o n i n t h e f a l l i n g p a t h o f a s i n g l e s o l i d b o d y i n t h e p r e s e n c e o f a n o b s t a c l e p l a c e d o n t h e s i d e w a l l o f t h e c l o s e d c h a n n e l.