I think in addition to the viscosity of your gel the 'stringy' flow depends

a) on the compressibility of your gel 

         (should be low because of water and/or oil content),

b) on the elastic behavior (including material creep and bending) of your tube

and

c) expecially on its non-reversable stress-strain properties caused by the tube material due to lateral and bending forces, which for example are affected by its geometry.

Creep and recovery used to know how much stress one material can sustain, If it is viscoelastic in nature it tries to come back to original position wen the load is taken away. You can play with different stress force and look on recovery.

Stringiness is due to the gel's elasticity. You can quantify this with creep tests. In particular, elasticity causes oscillations in the creep curve at short times. Type "Baravian creep" into Google Scholar. You will find pdfs of several papers on Researchgate that show how to analyze the results.

Christophe Baravian was my scientfic buddy. He died far too young, RIP.

My reply builds upon the stringiness being due to the gel elasticity. A creep test will resolve elasticity (the immediate strain with application of stress and reversible strain in recovery when stress is removed). The viscoelastic response is the time dependent strain after application of stress, however the viscoelastic response is superimposed with the viscous flow that is irreversible. The viscoelastic component is resolved in a recovery step after stress is removed. Recovery should give an immediate, equal and opposite elastic component followed by an exponential (sometimes better fitted by a stretched exponential function, such as a Weibull function). After recovery, which is recommended to be over four times the creep time, the remaining strain is permanent and due to viscous flow.

An alternative method is to perform dynamic rheology (using a shear stress frequency) and obtain the elastic shear or storage modulus (G') and the viscoelastic shear or loss modulus (G"). There should be no viscous flow because the experiment must be performed within the linear viscoelastic region (about 1 % strain). Frequency dependence will reveal changes in relative G' and G" with rate, the ratio of G"/G' = tan∂ is the the damping factor. With higher frequency G' should predominate over G" and a gel point is defined as the crossover frequency of G' and G" (tan∂ = 1), where elasticity begins to predominate over viscoelasticity.

We have developed a test on stringiness of aqueous starch pastes based on pumping the paste through an orifice of known diameter from a motor-driven syringe pump at constant speed along a graduated scale. The process was monitored by image analysis of a high speed video record. Measurable quantities were thread length and drop time. From these parameters also the average thread diameter and hence the extension ratio can be obtained. Results were correlated with shear viscosity (at 1/s) and storage modulus (at 1 rad/s). At a given viscosity the stringiness decreases with increasing modulus. The method has been published by P.A.M. Steeneken and A.J.J. Woortman, Food Hydrocolloids 5 (1991) 147-149. A more detailed analysis has been reported by P.A.M. Steeneken, A.J.J. Woortman. Stringiness of aqueous starch pastes, in: E. Dickinson, P. Walstra (eds). Food Colloids and Polymers: Stability and Mechanical Properties, pp. 147-156. Royal Society of Chemistry, Cambridge (1993). The full tekst can be retrieved from Google Scholar by looking for 'P.A.M. Steeneken, A.J.J. Woortman. Stringiness of aqueous starch pastes'. I am not sure the text can be downloaded. If not, this has to be done via a 'Print Screen' protocol.

We also performed creep tests on these pastes. 'Short' pastes showed nearly complete elastic recovery at low stresses and displayed a rather sudden transition to viscous flow-dominated response above a clearly marked yield strain. In 'long', i.e. stringy pastes this transition was much more gradual and a definite yield strain was difficult to observe. This work has also been published as a book chapter, but it is not covered by Google Scholar. [P.A.M. Steeneken, A.J.J. Woortman. Stringiness of aqueous starch pastes: relation with shear modulus and viscosity, in: F. Meuser, D.J. Manners, W. Seibel (eds). Progress in Plant Polymeric Carbohydrate Research, pp. 95-98. Behr's Verlag, Hamburg (1995).]

Please note that the reported trends may not be universally valid: starch pastes are microgel suspensions.