Free surfaces

The results of an experimental research activity aimed at the system setup of the Stress Pattern Analysis by Measuring Thermal Emission used to measure the sum of the principal stresses of the free surface are presented. 

Modelling of steady-state free surface flow corresponds to the solution of a boundary value problem while moving boundary tracking is, in general, viewed as an initial value problem. Therefore, classification of existing methods on the basis of their suitability for boundary value or initial value problems has also been advocated. 

Free surface density functions calculated at step 8 are used as the initial conditions to update the current position of the surface using the following integration... 

An example describing the application of this algorithm to the finite element modelling of free surface flow of a Maxwell fluid is given in Chapter 5. 

Nichols, B. D., Hirt, C. W. and Hitchkiss, R. S., 1980. SOLA-VOF a solution algorithm for transient fluid flow with multiple free surface boundaries. Los Alamos Scientific Laboratories Report No. La-8355, Los Alamos, NM. 

Petera, J. and Nassehi, V., 1996. Finite element modelling of free surface viscoelastic flows with particular application to rubber mixing. Int. J. Numer. Methods Fluids 23, 1117-1132. 

Sillinian, W. J. and Scriven, L. E., 1980. Separating flow near a static contact line slip at a wall and shape of a free surface.. /. Comput. Phys. 34, 287-313. 

As described in Chapter 3, Section 5.1 the application of the VOF scheme in an Eulerian framework depends on the solution of the continuity equation for the free boundary (Equation (3.69)) with the model equations. The developed algorithm for the solution of the described model equations and updating of the free surface boundaries is as follows ... 

Step 2 an initial configuration representing the partially filled discretized domain is considered and an array consisting of the appropriate values of F - 1, 0.5 and 0 for nodes containing fluid, free surface boundary and air, respectively, is prepared. The sets of initial values for the nodal velocity, pressure and temperature fields in the solution domain are assumed and stored as input arrays. An array containing the boundary conditions along the external boundaries of the solution domain is prepared and stored. 

Step 8 - the new values of the nodal velocities found at the end of step 7 are used as input and the free surface equation is solved. 

Step 9 - using updated values of the free surface function the location of the free surfaces are identified and the positions of each phase in the current flow domain are marked accordingly. 

Initial distribution and the predicted free surface boundaries within the twin-blade mixer represented by the mesh configurations shown in Figure 5.4, after 30, 60 and 90° rotation of the left blade are presented in Figures 5.5a to 5.5d, respectively. Samples of the predicted velocity fields after 30 and 45 ° rotation of the left rotor are shown in Figures 5.6a to 5.6b, respectively. The finite element... 

Figure 5.8 The finite element mesh used to model free surface flow in example 5.2.1...

Nassehi, V. and Ghoreishy, M. H. R., 1997. Simulation of free surface flow in partially filled internal mixers. Int. Poly. Process. XII, 346-353. 

The term adsorption appears to have been introduced by Kayser in 1881 to connote the condensation of gases on free surfaces, in contradistinction to... 

The distance from the crack tip, along the X-axis, at which the von Mises equivalent stress falls below the yield stress, defines the size of the plastic zone, r. For the plane stress case of unconstrained yielding, which corresponds to the free surface of the specimen in Figure 4, this gives... 

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