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Added: Central grading using a 5th order function (credit T. Gerasimov)

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This commit is contained in:
Knut Morten Okstad 2016-12-15 14:42:02 +01:00
parent c6575b6d5d
commit b4c6e90593
3 changed files with 55 additions and 1 deletions
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doc/mesh-grading-function.pdf Normal file
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13
src/Utility/Test/TestUtilities.C
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@ -34,7 +34,7 @@ TEST(TestUtilities, ParseIntegers)
TEST(TestUtilities, ParseKnots)
{
std::string simple("0 0 0.5 0.9 1.0");
std::string simple("xi 0 0.5 0.9 1.0");
strtok(const_cast<char*>(simple.c_str())," ");
std::vector<double> xi;
utl::parseKnots(xi);
@ -43,6 +43,17 @@ TEST(TestUtilities, ParseKnots)
ASSERT_FLOAT_EQ(xi[1], 0.5);
ASSERT_FLOAT_EQ(xi[2], 0.9);
ASSERT_FLOAT_EQ(xi[3], 1.0);
std::string graded5("xi C5 79 0.01 2.0");
strtok(const_cast<char*>(graded5.c_str())," ");
xi.clear();
utl::parseKnots(xi);
EXPECT_EQ(xi.size(), 79U);
EXPECT_FLOAT_EQ(xi[39], 0.5);
EXPECT_FLOAT_EQ(xi.front()+xi.back(), 1.0);
for (size_t i = 0; i < xi.size(); i++)
std::cout <<"xi["<< i <<"] = "<< xi[i] << std::endl;
}
TEST(TestUtilities, ReadLine)

43
src/Utility/Utilities.C
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@ -32,11 +32,53 @@ void utl::parseIntegers (std::vector<int>& values, const char* argv)
}
/*!
If the first character of the first token is a digit, it is assumed that
the knot values are listed explicitly by the remaining tokens. Otherwise,
various mesh grading schemes are assumed with the following syntax:
<UL>
<LI>G n alpha xi1 xi2 - Geometric grading</LI>
<LI>B n alpha xi1 xi2 - Biased geometric grading</LI>
<LI>C n alpha xi1 xi2 - Centered geometric grading</LI>
<LI>C5 n X1 X2 xi1 xi2 - Centred grading based on a 5th order function</LI>
</UL>
In each case the starting and ending knot values, xi1 and xi2, are optional.
If not specified, 0.0 and 1.0 is assumed.
The 4th scheme was proposed by Tymofiy Gerasimov 14.12.2016, and is described
in the file mesh-grading-function.pdf located in the doc folder.
*/
bool utl::parseKnots (std::vector<Real>& xi)
{
char* cline = strtok(nullptr," ");
if (!cline)
return false;
else if (toupper(cline[0]) == 'C' && cline[1] == '5')
{
// Centred grading using a 5'th order polynomial
int nX = atoi(strtok(nullptr," "));
double X1 = (cline = strtok(nullptr," ")) ? atof(cline) : 1.0;
double X2 = (cline = strtok(nullptr," ")) ? atof(cline) : 1.0;
double y0 = (cline = strtok(nullptr," ")) ? atof(cline) : 0.0;
double y1 = (cline = strtok(nullptr," ")) ? atof(cline) : 1.0;
double dy = y1 - y0;
if (nX < 2 || nX%2 == 0 ||
X1 <= 0.0 || X1 >= 1.0 || X2 <= 1.0 ||
y0 < 0.0 || dy <= 0.0 || y1 > 1.0)
return false;
double A = ( 16.0*X1 + 8.0*X2 - 24.0)*dy;
double B = (-40.0*X1 - 20.0*X2 + 60.0)*dy;
double C = ( 32.0*X1 + 18.0*X2 - 50.0)*dy;
double E = ( -8.0*X1 - 7.0*X2 + 15.0)*dy;
double F = X2*dy;
dy /= (1+nX);
double y = y0 + dy;
if (y0 > 0.0) xi.push_back(y0);
for (int i = 0; i < nX; i++, y += dy)
xi.push_back(((((A*y+B)*y+C)*y+E)*y+F)*y+y0);
if (y1 < 1.0) xi.push_back(y1);
}
else if (isalpha(cline[0]))
{
// Geometric grading
@ -48,6 +90,7 @@ bool utl::parseKnots (std::vector<Real>& xi)
double xi2 = (cline = strtok(nullptr," ")) ? atof(cline) : 1.0;
if (xi1 < 0.0 || xi2 <= xi1 || xi2 > 1.0 || ru < 1)
return false;
if (biased && ru > 1 && alpha != 1.0)
alpha = pow(alpha,1.0/double(ru));
else if (centred && ru > 1)