# Two-Phase Pressure Drops in Screen-Plate Bubble Column

I am reading the paper A Correlation of Two-Phase Pressure Drops in Screen-Plate Bubble Column

The goal of the paper is to come up with a regression model for a correction factor (denoted $$K$$) for a separated flow model $$(2)-(3)$$. My question is in regards to the full regression model in equation $$(7)$$. Does the form of the full-model equation, i.e. $$K=\alpha_0\, u_G^{\alpha_1}\,\nu_L^{\alpha_2}\,\left(\frac{u_G}{u_G+u_L}\right)^{\alpha_3}\,d_0^{\alpha_4},$$ have a theoretical justification? I know that many times in regression analysis theoretical knowledge is used to help determine the proper form of a model so I was not sure if theoretical considerations were used here to come up with the general form of $$(7)$$. I should mention now that I am trained in mathematics and not chemical engineering. Any help would be greatly appreciated.