The paper handles the subject of the modelling and simulation of the flow inside a centrifugal pump through non-cavitating and cavitating conditions. Operating under cavitation state is so perilous to a pump and can considerably reduce its lifetime service. Hence, to provide highly reliable pumps, it is essential to comprehend the inner flow of pumps. The investigated centrifugal pump comprises five backward curved-bladed impeller running at 900 rpm. The modelling process started with an unsteady numerical analysis under non-cavitating conditions to validate the numerical model and the solver comparing with the available testing data. Due to high Reynolds numbers, turbulence effects have been taken into account by unsteady RANS methods using an SST-SAS turbulence model. The obtained pump performances were numerically compared with the experimental ones, and the outcome shows an acceptable agreement between both. The temporal distribution of the internal flow parameters such as pressure and velocity was then studied. Furthermore, basic investigations of cavitating flow around 3D NACA66-MOD profile using a recently developed and validate cavitation model was established. The verification of the numerical simulation validity was based on comparing calculated and experimental results and presented good agreement. Finally, a 3D simulation of the inception of the cavitating pocket inside the centrifugal pump is performed to analyze the impact of the cavitation in the decrease of the head and efficiency.

Objective: Social anxiety refers to an excessive concern or fear about social situations. It seems that social media, which has become one of the most popular and effective tools for communication today, can be one of the contexts of social anxiety. Due to the lack of a Persian instrument to assess social anxiety in the context of social networks, the current study was undertaken to analyze the psychometric criteria of the Iranian version of the Social Anxiety Scale for Social Media Users (SAS-SMU). The SAS-SMU is a 21-item questionnaire designed by Alkis and colleagues (2017) to measure social anxiety emerging from the social media platforms. Method: In this study, a total of 842 participants within the age range of 11 to 82 years old (mean age 33. 11 ± 12. 134), 59% female) answered the questions in an online survey. The original version of the scale was translated into Persian using the back translation procedure. All participants completed a Demographic Questionnaire, the SAS-SMU, and the Beck Anxiety Inventory. In order to analyze the collected data, internal and external consistency, factor analysis, construct validity, and confirmatory factor analysis (CFA) were examined. A significance level of less than 0. 05 was considered to determine statistical significance. Results: Four subscales were obtained from the exploratory factor analysis (SCA, PCA, IA, and SEA), which were confirmed by the confirmatory factor analysis. Cronbach's alpha for internal consistency was found to be 0. 931 for the total scale and 0. 920, 0. 846, 0. 901, 0. 828 for SCA, PCA, IA, and SEA, respectively. In addition, the test-retest scores of 30 participants (interval: between 2 to 3 weeks) for all four subscales (SCA = 0. 641, PCA = 0. 773, IA = 0. 688, SEA = 0. 727) indicated acceptable stability of the questionnaire over time. Conclusion: This study validates the Persian version of the SAS-SMU for use in studies in the field of psychological problems related to social media and online communications.