************************************* **Lower Velocity Function Constants** ************************************* :: Lower Velocity Function Constants = {model_name} ----------------------- **Description / Usage** ----------------------- This card takes the specification of the Lower-wall velocity function for the confined channel lubrication capability, or the lub_p equation. This function specifies the velocity of the Lower channel wall as a function of time. Currently two models for {model_name} are permissible: +--------------------------+-------------------------------------------------------------------------------------+ |**CONSTANT** |This model invokes a squeeze/separation velocity uniformly across the entire material| | |region, viz. the two walls are brought together/apart at a constant rate. This option| | |requires two floating point values | | | | | | * is the velocity component in the x-direction. L/t | | | * is the velocity component in the y-direction. L/t | | | * is the velocity component in the z-direction. L/t (NOTE: this is usually | | | taken as zero as it is set in the Lower Wall Height Function model) | +--------------------------+-------------------------------------------------------------------------------------+ |**SLIDER_POLY_TIME** |This model implements a spatially-uniform velocity in the x-direction that is | | |specified as a polynomial in time. The value of time may be scaled by a given scaling| | |factor and the polynomial may have an unlimited number of terms. | | | | | | * is the time scaling factor | | | * are the coefficients in front of the t^(i-2) term | +--------------------------+-------------------------------------------------------------------------------------+ .. figure:: /figures/490_goma_physics.png :align: center :width: 90% +--------------------------+-------------------------------------------------------------------------------------+ |**ROLL** |This model invokes a wall velocity which corresponds to a rolling-motion. This model | | |takes nine constants ???? : | | | | | | * Roll radius, L. | | | * x-coordinate of axis origin, L. | | | * y-coordinate of axis orgin, L. | | | * z-coordinate of axis origin, L. | | | * Direction angle 1 of rotation axis | | | * Direction angle 2of rotation axis | | | * Direction angle 3of rotation axis | | | * Squeeze rate. | | | * rotation rate | +--------------------------+-------------------------------------------------------------------------------------+ |**TANGENTIAL_ROTATE** |This model allows a unique specification of tangential motion in a lubrication shell | | |element. Previous implementations allowed specification only in terms of coordinate | | |direction, but this option can be used to rotate a cylinder. Five floats are required| | | | | | * x-comnponent of a vector tangential to the shell. This vector must never | | | be normal to the shell. It is then projected onto the shell. | | | * y-comnponent of a vector tangential to the shell. | | | * z-comnponent of a vector tangential to the shell. | | | * U1, or scalar speed of wall velocity in a direction determined by the | | | cross product ot the tangent vector and the normal vector to the shell. (L/t) | | | * U2 scalar speed component in direction normal to U1. (L/t) | +--------------------------+-------------------------------------------------------------------------------------+ ------------ **Examples** ------------ Following is a sample card: :: Lower Velocity Function Constants = CONSTANT {v_x= -0.001} {vy=0.00} {vz=0} This card results in an Lower wall speed of -0.001 in the x-direction which is tangential to the substrate, thus generating a Couette component to the flow field. ------------------------- **Technical Discussion** ------------------------- For non-curved shell meshes, most of the time they are oriented with the x-, y-, or zplane. This card is aimed at applying a tangential motion to that plane, and so one of the three components is usually zero.