Basic unit processes implemented in C. Each function computes the data for a new node based on information from other nodes. The functions are computationally intensive and access the internals of the node data structure directly. Thus, we believe that the implementation is faster and tidier than a pure Tcl implementation -- at least we hope so.
Most of these functions involve some iteration.
The parameters for convergence check are:
max_iteration = 15
position_tolerance = 1.0e-5
int InteriorNode( int node1, int node2, int node4 )
Purpose: Calculate an interior point from two initial points.
Input :
node1 : index of initial point along C- characteristic
node2 : index of initial point along C+ characteristic
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be
created for the solution point.
Output :
Returns the index of the solution point or a value of -1
if there has been a failure.
(Available from the Tcl interpreter.)
int InsertNode( int node1, int node2, int node4, double alpha )
Purpose: Insert a node (node4) in between two initial
nodes (node1 and node2).
If node1 and node2 are adjacent nodes along a characteristic line,
node4 will be connected in between.
Input :
node1 : index of initial point 1
node2 : index of initial point 2
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be
created for the solution point.
alpha : fraction that node4 is like node2;
n4.value = alpha n2.value + (1-alpha) n1.value
Output :
Returns the index of the solution point or a value of -1
if there has been a failure.
(Available from the Tcl interpreter.)
int CMinusWallNode( int iw, int node1, int node4 )
Purpose: Calculate a wall point from one initial (C-) point.
Input :
iw : Index of selected wall.
node1 : index of initial point along C- characteristic
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be
created for the solution point.
Output :
Returns the index of the solution point or a value of -1
if there has been a failure.
(Available from the Tcl interpreter.)
int CPlusWallNode( int iw, int node2, int node4 )
Purpose: Calculate a wall point from one upstream (C+) point.
Input :
iw : index of the wall
node2 : index of initial point along C+ characteristic
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be
created for the solution point.
Output :
Returns the index of the solution point or a value of -1
if there has been a failure.
(Available from the Tcl interpreter.)
int CPlusFreeBndyNode( int node0, int node2, int node4 )
Purpose: Calculate a free-boundary point from one point (node0)
already on the boundary and one point (node2)
on a C+ characteristic.
Input :
node0 : index of initial point along C0 streamline
node2 : index of initial point along C+ characteristic
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be
created for the solution point.
Output :
Returns the index of the solution point or a value of -1
if there has been a failure.
(Available from the Tcl interpreter.)
int CMinusFreeBndyNode( int node0, int node1, int node4 )
Purpose: Calculate a free-boundary point from one point (node0)
already on the boundary and one point (node1)
on a C- characteristic.
Input :
node0 : index of initial point along C0 streamline
node1 : index of initial point along C- characteristic
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be
created for the solution point.
Output :
Returns the index of the solution point or a value of -1
if there has been a failure.
(Available from the Tcl interpreter.)
int AddStreamNode( int node0, int node1, int node2, int node4,
int test_only )
Purpose: Calculate a new streamline node, extending the streamline
to the line joining nodeA and nodeB.
Input :
node0 : index of initial point on the streamline
node1 : index of first initial interpolation point
node2 : index of second initial interpolation point
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be
created for the solution point.
test_only : flag to indicate whether we want to test for intersection only
or if we actually want to add the node to the streamline
test_only == 0 : add the node
test_only == 1 : test for intersection only
Output :
if test_only == 0 :
returns the index of the solution point or a value of 0
if there has been a failure.
if test_only == 1 :
returns 1 if intersection occurred between nodes 1 and 2.
A value of 0 indicates that intersection did not occur
between nodes 1 and 2.
(Available from the Tcl interpreter.)
int StepStreamNode( int node0, int node4, double dL )
Purpose: Calculate a new streamline node, extending the streamline
by length dL
Input :
node0 : index of initial point on the streamline
node4 : index of solution point (may have a value of -1)
dL : step-size along streamline;
A positive value will step downstream while a negative
value will step upstream.
If -1 is specified as the index for node4, a new node will be
created for the solution point.
Output :
Returns the index of the solution point or a value of -1
if there has been a failure. One possible failure is that
there are no nodes close enough to include in the interpolation phase.
(Available from the Tcl interpreter.)
int InterpolateNode( double x_point, double y_point, double R, int node4 )
Purpose: Locate a new node at coordinates (x,y), interpolating
the node's properties from other near-by nodes.
Input :
x_point,
y_point : coordinates of the new node
R : radius-of-influence for the Shepard interpolation
node4 : index of solution point (may have a value of -1)
If -1 is specified as the index for node4, a new node will be
created for the solution point.
Output :
Returns the index of the solution point or a value of -1
if there has been a failure. One possible failure is that
there are no nodes close enough to include in the interpolation.
(Available from the Tcl interpreter.)