*********************************** **Lower Height Function Constants** *********************************** :: Lower Height Function Constants = {model_name} ----------------------- **Description / Usage** ----------------------- This card takes the specification of the lower-height function for the confined channel lubrication capability, or the lub_p equation. This function specifies the height of the channel versus distance and time. Currently three models for {model_name} are permissible: +--------------------------+-------------------------------------------------------------------------------------+ |**CONSTANT_SPEED** |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 | | | | | | * the separation velocity (rate) in units of length/time | | | * the initial wall separation in units of length | | | * An OPTIONAL parameter which scales the addition of an external field | | | called “HEIGHT” which is read in using the External Field or External Pixel Field | | | capabilities. If this field is present, the value of it is added to the height | | | calculated with this model. | +--------------------------+-------------------------------------------------------------------------------------+ |**ROLL_ON** |This model invokes a squeeze/separation velocity in a hinging-motion along one | | |boundary. The model is best explained with the figure in the technical discussion | | |section. The equation for the gap h as a function of time and the input parameters | | |(floats) is as follows: | | | | | | * is x0 in units of length | | | * is hlow in units of length | | | * is h Δ, in units of length | | | * is the verticle separation velocity (if negative then squeeze velocity) | | | in units of length/time | | | * is the length of the plate, L. | +--------------------------+-------------------------------------------------------------------------------------+ .. figure:: /figures/488_goma_physics.png :align: center :width: 90% +--------------------------+-------------------------------------------------------------------------------------+ |**ROLL** |This model is used for a roll coating geometry. This option requires 8 floats: | | | | | | * x-coordinate of origin, L. | | | * y-coordinate of orgin, L. | | | * z-coordinate of origin, L. | | | * Direction angle 1 of rotation axis | | | * Direction angle 2 of rotation axis | | | * Direction angle 3 of rotation axis | | | * rotation speed L/t. | +--------------------------+-------------------------------------------------------------------------------------+ |**TABLE** |Please see discussion at the beginning of the material properties Chapter 5 for input| | |description and options. Most likely *character_string1* will be **LOWER_DISTANCE** | |{LINEAR | BILINEAR} |This option is good for inputing table geometry versus distance. Specifically, an | |[integer2] [FILE = filenm]|arbitrary lower height function model is input as a function of the x-direction | | |coordinate of the Lower Velocity Function model. This option in turn requires the use| | |of SLIDER_POLY_TIME lower velocity function model. See example below. | +--------------------------+-------------------------------------------------------------------------------------+ ------------ **Examples** ------------ Following is a sample card: :: Lower Height Function Constants = CONSTANT_SPEED {v_sq = -0.001} {h_i=0.001} This results in an lower wall speed of 0.001 in a direction which reduces the gap, which is initial 0.001. In another example: Lower Height Function Constants = TABLE 2 LOWER_DISTANCE 0 LINEAR FILE=shell.dat where shell.dat is a table with 2 columns, the first the position, the second the height. ------------------------- **Technical Discussion** ------------------------- The material function model ROLL_ON prescribes the squeezing/separation motion of two non-parallel flate plates about a hinge point, as shown in the figure below.