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The purpose of this paper is to determine the thermo-gravitational convective state of a non-Fourier fluid layer of the single-phase-lagging type, heated from below. Unlike existing methodologies, the spectral modes are not imposed arbitrarily. They are systematically identified by expanding the spectral coefficients in terms of the relative departure in the post-critical Rayleigh number (perturbation parameter). The number and type of modes is determined to each order in the expansion. Non-Fourier effects become important whenever the relaxation time (delay in the response of the heat flux with respect to the temperature gradient) is of the same order of magnitude as process time.

In the spectral method the flow and temperature fields are expanded periodically along the layer and orthonormal shape functions are used in the transverse direction. A perturbation approach is developed to solve the nonlinear spectral system in the post-critical range.

The Nusselt number increases with non-Fourier effect as suggested in experiments in microscale and nanofluid convection.

Unlike existing nonlinear formulations for RB thermal convection, the present combined spectral-perturbation approach provides a systematic method for mode selection.

The post-critical convective state for Rayleigh-Benard (RB) convection is studied using a nonlinear spectral-amplitude-perturbation approach in a fluid layer heated from below. The paper aims to discuss these issues.

In the spectral method the flow and temperature fields are expanded periodically along the layer and orthonormal shape functions are used in the transverse direction. A combined amplitude-perturbation approach is developed to solve the nonlinear spectral system in the post-critical range, even far from the linear stability threshold. Also, to leading order, the Lorenz model is recovered.

It is found that very small Prandtl numbers (Pr < 0.1) can change the Nusselt number, when terms to O(ε5/2) and higher are considered. However, to lower orders the Prandtl number does not affect the results. Variation of the Nusselt number to different orders is found to be highly consistent. Comparison with experimental results is made and a very good qualitative agreement is observed, even far from the linear threshold.

Unlike existing nonlinear formulations for RB thermal convection, the present combined spectral-perturbation approach provides a systematic method for mode selection. The number and type of modes to be included are directly related to the post-critical Rayleigh number. The method is not limited to the weakly nonlinear range.

This study aims to investigate the relationship between travel motivation, perceived risks, travel constraints and perceived beneficial destination image that leads to visit intention among Middle-Eastern medical tourists. Some previous studies have explained these factors in detail, however, studies that explore the relationship between these factors in the Iranian context is scarce. Moreover, there are relatively very few studies, which focused on actual medical tourists in empirical investigation, therefore, there is still a lack of clarity in the literature regarding travel behavior and travel decision-making of medical tourists.

A quantitative study was performed on 161 Middle-Eastern medical tourists who visited Iran in early months of 2018. Purposive sampling method was used to collect the data from two private hospitals. Structural equation modeling with partial least square (PLS) approach was used and PLS 3.2.8 data analysis tool was used to test the hypotheses.

The data analysis results have found that perceived destination image was the strongest predictor of visit intention among medical tourists. The results have also found a positive effect of travel motivation and negative effect of perceived travel risks on perceived beneficial destination image.

This study aims to enrich the body of knowledge by investigating the relationship between the factors, which have important roles in travel behavior and decision-making of medical tourists. The study also bridges the gap in the literature by explaining the behavior of actual medical tourists. The findings of the study provide the much needed insight on the behavioral intention of medical tourists, which will help the service providers and policymakers to reform their strategies and policies accordingly.